The paper contributes to the debate on top performance in research productivity, its persistence over time, and the impact of gender. It uses a panel data set comprising the publications of all biomedical and exact scientists at the University of Leuven in the period 1992 to 2001. We find that women have a significant lower probability of reaching top performance for the first time in their career, particularly for top performance measured through citations, but there is no evidence for a gender bias hindering repeated top performance. On the contrary, women seem to persist in top performance more easily than men do.