All rejection episodes that occurred from 1990 to 1995 treated by the University of Colorado renal transplant service were evaluated through a review of patient charts. Seventy-one episodes of rejection were treated initially with pulse steroids consisting of pulse methylprednisolone, 500 mg/d for 3 days, with sufficient follow-up to determine whether the patient would respond to this treatment. There was no difference between responders and nonresponders to methylprednisolone treatment with respect to serum creatinine level at time of diagnosis, age of allograft, nadir serum creatinine level, or presence of oliguria. The time course of change in serum creatinine levels (in milligrams per deciliter) in responders and nonresponders was similar until day 5, at which time significant differences could be seen (P < 0.01). In the 34 patients treated with OKT3 (muromonab-CD3), statistically significant differences between responders and nonresponders were only seen at day 14, but the small number of nonresponders (n = 4) makes this analysis inconclusive. Based on these data, it appears one cannot truly evaluate whether a patient will respond to three daily pulses of methylprednisolone until at least 3 days have passed since completion of therapy.