During the past few decades there has been a significantly increasing trend in germ cell tumours all over the world, particularly in countries with Caucasian populations. The changes in incidence have occurred so fast that only environmental factors can explain this development. This review focuses on the hypothesis that testicular germ cell cancer, which originates from germ cell neoplasia in situ, is of foetal origin and associated with other male reproductive problems through a testicular dysgenesis syndrome, also including foetal origin of impaired spermatogenesis, hypospadias and cryptorchidism. There is little doubt that environmental factors associated with modern lifestyles have - in a broad sense - had an adverse influence on male reproductive health. The hypothesis that exposure to endocrine-disrupting chemicals plays a fundamental role in this trend is plausible. This is based on evidence from animal studies that demonstrate adverse reproductive effects caused by a number of endocrine-disrupting chemicals to which humans are exposed as part of our modern lifestyle.