Early results of a prospective, randomized trial of active, specific immunotherapy adjunctive to nephrectomy in all stages of RCC are presented. Forty-three patients with median followup of 30 m, who were randomly allocated to either immuno-hormonotherapy arm (IMT), or hormonotherapy alone (HT), are evaluated in terms of progression-free interval (PFI) and overall survival by life table method. Immunotherapy consisted of autologous irradiated tumor cells (AITC), admixed with bacillus Calmette-Guérin (Glaxo) administered by the intradermal and endolymphatic route. Clinical results of this study show only a trend for advantage of the experimental (IMT) arm over the control (HT) arm, this trend did not reach statistical significance level: prolongation of disease free period in stages I-III with localized disease (p less than 0.1) and prolongation of survival in patients with metastatic disease (p less than 0.07). A correlation was established between induction of cutaneous delayed hypersensitivity (DTH) to AITC and prolonged PFI and survival: patients with positive DTH had a significantly better course of disease than those who could not be converted to positivity after repeated immunizations. Positive in vitro leukocyte migration inhibition against autologous tumor preparations correlates well with positive in vivo cutaneous DTH. Some immunological aspects of active immunization with autologous tumor cells are discussed.