Background. Intravesical instillations with bacillus Calmette-Gué rin (BCG) is considered the treatment of choice in the prophylaxis of high-grade superficial bladder carcinoma and in the treatment of carcinoma in situ (CIS) of the bladder. Methods. There is no previous experience with BCG treatment in patients with renal transplantation. Theoretically, immunosuppression is a contraindication because of the risk of severe morbidity and sepsis. We present our experience with endovesical BCG in three renal transplant patients, under immunosuppressive treatment, with high-grade superficial bladder cancer and CIS. Results. Two patients are free of disease at 17 and 60 months. One patient developed disease recurrence and underwent a radical cystectomy. There was neither change in renal function nor any clinical evidence of tuberculous infection. Conclusions. Intravesical BCG in superficial bladder cancer and/or CIS is a valid option, with no added morbidity to renal transplant patients.