The invention relates to a self-priming pump (1) having a housing (9), an inlet (4) and an outlet (5), having a first impeller (15) with a first pump section (17) that is arranged in a first chamber (18), and a second impeller (16) with a second pump section (19) that is arranged a second chamber (20), and a shaft section (25) that is arranged between the pump sections (17, 19), which shaft section (25) comprises a shaft end (26) and passes through an opening (24) of a housing wall (23). According to the invention, in order to improve the net positive suction head of the pump (1), the shaft section (25) is formed in a tapering manner from the shaft end (26) to a necking (27) between the necking (27) and the shaft end (26), and the first impeller (15) and shaft section (25) have a smooth course between the necking (27) and the first pump section (17).