The western Issaean necropolis (Martvilo site) and the eastern Issean necropolis (Vlaška njiva site) are two partially archaeologically explored burial landscapes of ancient Issa (Vis, the island of Vis), a Greek island polity which, according to scientific tradition, was founded by the Greeks from Syracuse during the 4th century BC. Rescue archeological excavations in the last century defined the segments of ancient cemeteries in Issa. On both necropoleis we simultaneously follow burials starting from the third quarter of the 4th century BC with its continuity in Roman times. In this dissertation, 63 burial units were analyzed for the first time. The graves were found during the archaeological research of the southwestern part of the Martvilo cemetery from 1976 to 1985. In the discovered graves, the skeletal remains of at least 50 deceased people were identified, with 799 various objects originating primarily from tomb assemblages. On the investigated segment of the necropolis, we can trace the earliest securely documented burials from the beginning of the 3rd century BC to the 1st century AD, corresponding to the period of Issa's prosperity, the loss of independence and the origins of Roman domination in Issa. From 22 burial units, an anthropological analysis confirmed the remains of at least 50 deceased individuals: 8 adult women (36%), 23 adult men (46%), five children (10%; one adolescent woman; four of unknown sex and age), while there are no data on the gender of the four deceased (8%). The osteological image of the deceased from the Martvilo necropolis complements the one from the Vlaška njiva necropolis. To that extent, the research that is in the focus of this doctoral dissertation represents a shift towards methodologically modern archaeological excavations, so the integral publication of their results is a significant scientific contribution to the knowledge of the burial customs of ancient Issa. The Issaean funerary ritual, consisting of multiple successive inhumation burials, is dominant throughout Hellenism; the most significant number of deceased recorded in one grave complex is nine, and in ten graves (15.9%) the remains of (at least) one dead individual were documented (of which only one skeleton was found in an intact tomb). Considering the state of the archaeological excavations on the island of Vis, we do not have information about the funeral customs of the indigenous population, but according to comparisons with the northern and central Dalmatian Iron Age indigenous grave sites, multiple successive burials were recorded in the Liburnian area, which are mainly feature of the Dalmatian cultural circle. Nevertheless, the multiple successive burials within the same grave architecture were documented in the eastern necropolis and a series of late classical and Hellenistic graves in Greek cities and indigenous centers in southern Italy (Apulia). They also occur in the Aegean, Peloponnese, NW Greece, Greek Macedonia, and Epirus. The practice of moving skeletal remains within one burial unit in order to create space for a new burial was also recorded in some of the above-mentioned archaeological sites, also in the segment of the investigated Martvilo necropolis, which dates from the 3rd century BC until the 1st century BC. One ceramic stamnoid urn with cremated human remains and bulbous unguentarium was placed in one 3rd century BC tomb – the practice can be interpreted in association with the close relations between Issa and the Roman cultural circle. Also, for the first time in the Martvilo necropolis, archaeological research has documented cremation burials in ordinary soil pits or ceramic jugs in the function of urns. According to grave goods, we date the earliest incineration burials on the Martvilo necropolis to the 2nd century BC. At the same time in the Vlaška njiva necropolis, we associate this transformation of the funeral ritual from inhumation to incineration with the phenomenon of Romanization. However, it is necessary to emphasize several methodological obstacles that directly affected the quality of the conclusions derived from this study. Primarily, the archaeological research that is in the focus of this dissertation began 47 years ago. Since several archaeologists were responsible for the excavations, the field documentation is heterogeneous, sometimes incomplete, and partially unavailable. Furthermore, despite seven relatively successive archaeological campaigns, the research was predominantly of a rescuing nature, and devastation of graves occurred even during the investigation. Only three tombs were found intact (4.8%), while the rest were partially and/or wholly disturbed in context and/or devastated. This doctoral dissertation's primary goal is to analyze and synthesize the characteristics, development, and changes of burial customs in ancient Issa during the Hellenistic period until the early Roman imperial period, derived from interpreting preserved material remains at the Martvilo site and available field/museum documentation. Therefore, the study focuses on the finds of grave architecture, grave finds, the deceased's body, the rites that took place around the grave units, and the spatial development of the western Issean necropolis. We are trying to reconstruct the segments of Issaeian burial customs based on various archaeological objects inside and outside the graves and around them. We base the analysis of the development and (dis)continuity of mortuary practices and their features primarily on a comparison with the burial practices documented in the Vlaška njiva necropolis, but also with synchronic necropoleis of residents of other Greek cities and members of the indigenous communities of the eastern and western shores of the Adriatic, southern Italy, and Sicily, expanding the geographical framework to the Ionian and Aegean areas, i.e., the entire Mediterranean. Burial customs reflect the dynamic and diverse commercial, economic, sociological, and cultural aspects of life in Issa, with a comprehensive analysis of which we reconsidered the status questionis of that Greek city which at the turn of the era was transformed into a settlement of the Roman citizens.