In this prospective randomized study, acute renal transplant rejections occurring in patients who received prophylactic OKT3 therapy were treated with either 3 pulses of 8 mg/kg methylprednisolone (MPS) in an alternate-day regimen (total dose 25 mg/kg in 1 week, H group, n = 24) or 5 daily pulses of 3 mg/kg MPS (total dose 17 mg/kg, L group, n = 22). Acute rejection was proven by biopsy in more than 85% of cases in both groups. No difference was observed in rejection reversal (H 88%, L 91%), graft losses in the following 3 months (H 11%, L 4%) or the time evolution of the serum creatinine levels. The number (H 14, L 21) as well as the nature and severity of infections were similar in both groups. Only one death occurred in a patient who received OKT3 rescue therapy for corticoresistant rejections and developed Epstein-Barr virus (EBV)-related lymphoma. In conclusion, low dose MPS pulses appear as effective and safe as a higher dose to reverse acute rejection occurring after OKT3 prophylaxis. Thus, we favour the use of the low dose regimen in these patients.