Seminoma of the testis is a model of a highly curable tumour. At presentation 75% of all seminoma of the testes cases have stage I disease (Zagars, 1991). The traditional management of these cases has been wide field, low dose radiotherapy to include the para-aortic and pelvic nodes (Fossa et al., 1989; Hanks et al., 1992). This approach has led to relapse free survival approaching 95% and cause specific survival of around 98% (Read et al., 1983; Hamilton er al 1986; Zagars, 1991). Alternative management strategies of surveillance and latterly adjuvant chemotherapy in this situation have been developed with the aim of reducing the low but recognised toxicities associated with radiotherapy. The major concerns with the radiotherapy described above are the radiation dose received by the contralateral testes (Jacobsen et al., 1997) and the potential carcinogenesis associated with radiotherapy (Travis et al., 1997). In theory, both of these effects are related to the volume and dose irradiated, and reduction of these parameters may be associated with benefit. In this study we have addressed the role of reduced volume together with reduction of the radiation dose and overall treatment time.