The topic of residual antibiotics in wastewater as a sanitary problem of the environment includes the problem of the presence of antibiotics in wastewater and their impact on the environment. The biggest cause of this problem is man who behaves recklessly, pollutes water and endangers the environment. There are numerous sources of antibiotics in the environment, but the largest share comes from the field of two medicines: human and veterinary. They are present in all aquatic media such as wastewater, surface water, groundwater or the marine environment. Although wastewater is treated according to well-defined methods and instructions, unfortunately, some part of antibiotics is still present in the purified water which is used in agriculture or animal husbandry. The paper presents different types of wastewater that affect the creation of sanitary environmental problems which are caused by various types of antibiotics such as macrolides, tetracyclines, quinolones, sulfonamides. Furthermore, the paper highlights the methods of determining antibiotics in wastewater and different ways of properly disposing of residual antibiotics. The paper also provides useful information on the types and quantities of residual antibiotics that measured in samples which were taken from Croatian water and water around the world.