The intention was to explore the relationship between fertility and testicular cancer, including the possibly treatment-induced changes over time in the post-diagnostic fertility. Data are from the Norwegian Cancer Registry, The Norwegian Population Register and the Population Censuses. By estimating Poisson regression models, birth rates among testicular cancer patients were compared with those of other men who had the same age, parity and duration since previous birth. Poisson regression models were also estimated to check whether men's parity has an effect on the cancer incidence. Fertility rates among testicular cancer patients born after 1935 and treated before 1991 decreased by roughly 30% when compared with the normal population. The introduction of cisplatin chemotherapy and of nerve-sparing RPLND in the 1980s seems to have enabled more patients with non-seminoma to father a child after treatment, or at least shortened the time to conception. Moreover, the risk of being diagnosed with seminoma is reduced with increasing parity. This suggests that the relatively low fertility after diagnosis may be partly due to the continuing inherent influence of a sub- or infecundity that also had a bearing on the development of the disease.