Purpose: We pooled data from randomized, double-blind, placebo-controlled trials to determine the frequency of adverse reactions among patients treated with cimetidine for acute acid-peptic disorders. Methods: Meta-analysis was used to analyze data obtained from a search of English language reports of trials of cimetidine in the ambulatory treatment of acute acid-peptic disorders that were published between January 1982 and April 1987. Results: Of 161 trials of cimetidine that we identified, 84 provided complete reporting of data on adverse reactions and, of these, 24 employed a randomized, double-blind, placebo-controlled design. Across these 24 trials, the overall rate of reported adverse reactions among 622 patients randomly assigned to receive cimetidine was 10.9%; the corresponding rate among 516 patients randomly assigned to receive placebo was 10.1%. This difference was not statistically significant (p >0.10), nor were any significant differences noted in the frequencies of reported central nervous system or gastrointestinal adverse reactions (p >0.10). Rates of adverse reactions also did not differ by dosage or trial duration. The overall rate of adverse reactions reported in the 60 trials that did not utilize a randomized, double-blind, placebo-controlled design was similar to the rate reported in those that did. Conclusion: Our findings suggest that the frequency of adverse reactions among patients receiving cimetidine for acute acid-peptic disorders is not significantly different from that of patients receiving placebo.