Disruption of the marine ecosystem is not an uncommon phenomenon. It occurs in the case of technical and accidental pollution originating from ships. International conventions and other national regulations control the pollution of the sea by oil by regulating the issue of oil discharge into the sea and determining the basic standards that must be met in order to protect the marine environment. The paper deals with the protection of the sea from oil pollution according to the MARPOL convention as one of the most important conventions in the field of protection of the sea from substances released by ships. The aim of the paper was to deal with the problem of oil pollution of the sea, as well as the principles and guidelines for preventing pollution according to the MARPOL convention. The paper shows the significance of the catastrophic consequences that non-compliance with regulations protecting the marine environment can lead to, and presents the most important rules from the MARPOL convention, which prohibits any form of sea pollution - leakage, discharge, ejection, spilling or emptying. The paper shows which technical measures to limit the release of harmful substances into the sea are prescribed by the MARPOL convention and which standards are set for shipbuilding. Also, the paper provides an overview of the convention conditions that must be met by the flag states in order to meet the standards for the protection of the sea from pollution.