We describe two unrelated men with a previously unreported combination of tumours. The first patient developed a right-sided testicular teratoma at the age of 25 years treated with orchidectomy. He went on to develop a left-sided seminoma at the age of 35 years, treated with orchidectomy followed by prophylactic para-aortic radiotherapy (30 Gy in 15 fractions). At the age of 48 years he developed a nodule in the left lobe of thyroid (AC4/Thy4 on FNA) treated with hemithyroidectomy followed by completion thyroidectomy for papillary carcinoma of the thyroid (pT4 Nx M0), followed by ablative radioiodine therapy (3700 MBq). The second patient developed a right-sided intermediate grade malignant testicular teratoma at the age of 19 years treated with radical orchidectomy. At that time biopsy from the left testis was normal with active spermatogenesis, but he subsequently developed a left-sided testicular seminoma with extensive intratubular germ cell neoplasia at the age of 25 years. This was also treated with radical orchidectomy after sperm storage, but radiotherapy was not deemed to be necessary. A year later he developed a solitary thyroid nodule (AC3 on FNA), treated with hemithyroidectomy and completion thyroidectomy for multifocal follicular variant of papillary carcinoma (pT2 Nx Mx), followed by ablative radioiodine therapy (3030 MBq). Neither patient had a family history of cancers. Both remain well on testosterone and thyroxine replacement with no evidence of tumour recurrence on continued surveillance. Random occurrence is a possible explanation for this previously unreported combination of tumours. However, an as yet undiscovered genetic predisposition (or environmental influence or both) would seem rather more likely.