Partial nephrectomy is classically indicated in patients with renal cell cancer on a single kidney, although a certain amount of debate continues on surgical technique: simple enucleation or true partial nephrectomy. Incidence of multifocal tumours has been estimated at 6 to 19.6%. The crucial problem for the surgeon is to recognize satellite tumours pre- and peroperatively since it has been estimated that 4 to 10% of renal cell carcinomas contain a multifocal disease unrecognized during surgery. Is conservative nephrectomy acceptable for patients with a functional contralateral kidney? There are several arguments in favour of the technique: fortuitously discovered tumours are generally smaller and in a less advanced stage, morbidity after conservative surgery is low compared with total nephrectomy, nephron sparing improves long-term renal function and survival at 3 to 5 years is 95 to 100%. The fact that the risk of cancer on the contralateral kidney is small (1 to 2%) compared with the risk of local recurrence and the lack of sufficiently long follow-up in large series are negative arguments. Conservative nephrectomy must therefore be considered as the best solution when nephron sparing is essential. Total nephrectomy remains the reference treatment in other cases although the discussion remains open for cases with small (< 2.5 cm) tumours.