Slawomir Rams Title: On quintic threefolds with triple points Abstract: We study the geometry of quintic threefolds X in P4 with only ordinary triple points as singularities. In particular, we show that if a quintic threefold X has a reducible hyperplane section then X has at most 10 ordinary triple points, and that this bound is sharp. We construct various examples of quintic threefolds with triple points and discuss their defect (this is joint project with prof. R. Kloosterman from Padva).