Numerous studies have shown that female scientists tend to publish significantly fewer publications than do their male colleagues. In this study, we have analyzed whether similar differences also can be found in terms of citation rates. Based on a large-scale study of 8,500 Norwegian researchers and more than 37,000 publications covering all areas of knowledge, we conclude that the publications of female researchers are less cited than are those of men, although the differences are not large. The gender differences in citation rates can be attributed to differences in productivity. There is a cumulative advantage effect of increasing publication output on citation rates. Since the women in our study publish significantly fewer publications than do men, they benefit less from this effect. The study also provides results on how publication and citation rates vary according to scientific position, age, and discipline.