The influence of donor age on the outcome of kidney transplantation (TX) was evaluated in 169 patients who received a primary cadaver kidney transplant at our center between September 16, 1984, and December 31, 1990. All the patients received cyclosporin A as part of the immunosuppressive protocol. Patients were grouped according to donor age: low donor age (LDA; donor age range 12-25 years), medium donor age (MDA; range 26-50 years) and higher donor age (HDA; range 51-66 years). There were no differences between groups in graft and patient survival, and multivariate analysis did not show any effect of donor age on those parameters. Proteinuria/day and number of rejection episodes did not differ between groups either. Immediate diuresis was more frequent in group LDA than in the other two groups (73.8, 54.7 and 57.1%, respectively; p < 0.05) and immediate diuresis resulted as a weak positive prognostic factor for graft outcome at multivariate analysis (p = 0.05). At both univariate and multivariate analyses, donor age resulted inversely correlated with creatinine clearance (CCr) at every period after TX but the 5th year, with r2 from 0.12 to 0.23 (p < 0.01). The LDA group had significantly better CCr than the HDA group at every period after TX but for the 5th year (the MDA group behaved intermediately).(ABSTRACT TRUNCATED AT 250 WORDS)