The objective of this study was to evaluate the modifications that renal transplantation produces on the quality of life (QOL) of patients with chronic renal failure (CRF) previously undergoing hemodialysis (HD) and to analyze the possible factors implicated. A multicenter study of QOL was performed on 1,023 patients undergoing dialysis, using as QOL indicators the Karnofsky Scale (KS) and the Sickness Impact Profile (SIP). Among this group, 93 patients received a renal transplant and QOL was re-studied in them; each subject, therefore, was his own control. In the 88 patients with a functioning graft, an improvement in QOL indices was globally observed; this improvement was much more marked in men than in women, for unclear reasons. Older age and greater prior comorbidity diminished the beneficial effects of transplantation.