Oosterhuis JW, Looijenga HJ. Current views on the pathogenesis of testicular germ cell tumours and perspectives for future research: Highlights of the 5th Copenhagen Workshop on Carcinoma in situ and Cancer of the Testis. APMIS 2003;111:280–9. This review article highlights the most important contributions presented at the 5th Copenhagen Workshop on Carcinoma in situ and Cancer of the Testis, which was held in Denmark, August 29–31, 2002. The major themes that emerged at the meeting are critically discussed and perspectives for future research in this field are presented.