Human germ cell tumours comprise a heterogeneous group of neoplasms which, based on pathobiological, genetic and clinical characteristics, can be subdivided into different entities. One of these subgroups relates to the so-called spermatocytic seminomas, benign tumours only found in the testis, preferentially in elderly men. Various developmental models for this type of germ cell tumour have been proposed and it is clear that spermatocytic seminoma has a pathogenesis independent from that of seminoma. A recent study examining expression of spermatogonial markers shows that spermatocytic seminomas are a heterogeneous group of tumours, with a supposed difference in origin, ie the majority from A(pale) or B spermatogonia, and a minority from A(dark) spermatogonia. However, this does not exclude an earlier cell of origin, possibly explaining the unique properties of this type of human germ cell tumour, with various counterparts in animals.