Stage I and IIA/B testicular seminoma represent approximately 45% of all testicular germ cell tumours. Due to the availability of highly efficient salvage treatment, the disease-specific survival in stage I seminoma is approximately 100%, irrespective of the choice of adjuvant treatment. Radiotherapy with 26 Gy to the paraaortic/paracaval lymph nodes yields excellent cure rates of 95 98% with a favourable profile of acute and late toxicity. Likewise, phase-II trials with single-agent carboplatinum systemic treatment have demonstrated a rate of relapse of 3-4% on average. However, carboplatinum chemotherapy has to be regarded as experimental until data of phase-III trials are available. Surveillance in stage I disease is conflicted with a rate of relapse of approximately 20%. However, 80% of the patients will avoid potentially toxic overtreatment by the watch-and-wait policy. In stage IIA/B seminoma, "dogleg" radiotherapy with 30 Gy and 36 Gy, respectively, provides high cure rates of 90-95%. Those patients relapsing will be salvaged in almost 100% of cases. Testicular intraepithelial neoplasia (TIN) is the common precursor lesion of testicular germ cell tumours except for spermatocytic seminoma. In case of TIN in a single testis or bilateral TIN, local radiotherapy with 18 Gy is recommended as standard treatment.