The authors report the experience of the investigators of the Groupe Français d'Immunotherapie in the treatment of metastatic renal cancer by cytokines based on several clinical trials conducted successively between 1991 and 1998. This group initially conducted a large-scale randomized trial reported in the New England Journal of Medicine in 1999, comparing three treatment regimens: intravenous interleukin-2, interferon alone and a combination of these two treatment modalities. The two cytokines demonstrated an additive effect allowing doubling of the response rate and the one-year progression-free survival. Unfortunately, this effect was not maintained in the long term and no overall survival difference was observed. Patients resistant to one of the two cytokines also failed to respond to the other cytokine administered subsequently. A subgroup of patients was identified with a probability of progression during treatment greater than 70% and a median survival of 6 months. These patients concomitantly presented initial metastases during the year following the diagnosis of renal cancer, involving several organs including the liver. Several subsequent trials testing the two cytokines by s.c. injection provided poor results, with low response rates, even in combination with 5-fluorouracil. In the French experience, s.c. cytokine regimens are therefore fairly disappointing. These results were taken into account in the ongoing evaluation programme (Percy programme) based on patient selection as a function of prognostic factors.