This report examines the dilemma that a patient, who was a doctor, faced on discovering that he was developing a second primary testicular tumour (seminoma) in a solitary testis. The usual treatment for this is radical orchidectomy. He rejected this on the grounds that he wanted to have children, and eventually decided on the use of single-agent carboplatin chemotherapy. Seventeen months after treatment, there was no evidence of tumour on MRI or ultrasound scanning and there is some recovery of spermatogenesis. So far, 13 of 14 patients treated with chemotherapy for metastatic disease (with the primary tumour being left in situ), which has normalized following treatment, have survived for more than 5 years without evidence of tumour recurrence. This approach could be a viable option for men with tumours in a solitary testis who have not completed their families. However, a larger prospective study is essential to determine whether this approach is safe, so that these patients will not have to bear the psychological burden of choosing between their chances of survival and the possibility of fathering children.