Sailing of tanker ships in specific navigation areas, such as narrow waterways, is a particularly delicate navigational venture, where one of the greatest related risks is grounding. Grounding of a tanker in a narrow waterway is an event that can cause many adverse consequences, the most important among them being environmental pollution, explosion or onboard fire damaging the ship, injuries and lost lives of crewmembers. Factors affecting the safety of tanker navigation in narrow waterways can be principally divided into geometric, traffic, meteorological and oceanological factors, ship design factors and marine equipment faults as well as human-related factors. With a view to minimizing the possibility of grounding or contact, the assessment of risks is to be considered indispensable and primarily aimed at influencing accident probability and/or consequence factors as its most important objective. The paper analyses the safety of tanker navigation in narrow waterways based on the assessment of risk of grounding. The event influential probability factors that are taken into consideration comprise the narrow waterway category, meteorological and oceanological conditions, traffic density and VTS coverage of the navigable area, while factors such as ship speed, bottom type, hull quality and loading condition are factors related to consequences. Using the risk assessment matrix, estimated values used for evaluation of the safety of tanker navigation in narrow waterways are assigned to probability factors and factors of consequences.