||The article describes an electronic database of selected marine piston combustion engines created for diagnostic purposes. The database was made for vessels of the biggest Polish shipowner. It is used for archiving and comparing measured parameters of diagnosed engines with model parameters. To facilitate the search for and use of required data, they have been collected and catalogued. For this purpose the database has been prepared by using a computer program included in the Microsoft Office suite. The database search relies on the details concerning the type of vessel. The fields displayed include such items as the year and place of construction, the parameters of the ship, flag, etc.. For each vessel special forms are available for main and auxiliary engines, enabling easy and quick check of the necessary parameters during operation of the engine. The database contains parameters of the main propulsion and auxiliary engines, as well as model characteristics to help determine the diagnostics, prognosis and genesis.