Abstract Background. The incidence of prostate cancer (PC) has increased during the last 15 years in Denmark, whereas the mortality has remained largely unchanged. This register study aimed to investigate the trends in PC incidence and mortality in Denmark 1978-2009 with special focus on the recent 15 years. Material and methods. From the nationwide Danish Cancer Registry and Register of Causes of Death, we obtained information on all cases of PC and all deaths in Denmark during 1978-2009. Age-standardised (World Standard Population) incidence and mortality rates were computed for five-year calendar periods (1978-2007) and a two-year calendar period (2008-2009). Trends in incidence rates were estimated for specific age groups, birth cohorts, and clinical stage. Results. The age-standardised incidence rate of PC increased from 29.2 per 100 000 person-years in 1978-1982 to 76.2 per 100 000 person-years in 2008-2009. The incidence increase began primarily in the mid-1990s. The corresponding mortality rates of PC remained largely unchanged during the entire study period; around 19 per 100 000 person-years. The incidence increase was most pronounced among men aged 60 + years. A clear pattern was also seen for selected birth cohorts, with increasing incidence rates among the youngest cohorts, and the highest relative increase in age-specific incidence rates was seen among men born between 1943 and 1947. The distribution of stage changed from 1998, with an increasing proportion of PC patients with localised disease. Conclusion. The observed increase in PC incidence during the period 1993-2009 in Denmark may be attributed primarily to increasing unsystematic use of prostate specific antigen (PSA) testing. The mortality rates remained stable during the same period suggesting that there is not yet any major influence of intensified PSA screening and more frequent use of curatively intended therapy on the overall prognosis of PC.