Objective: The objective of this study was to study the frequency and determinants of breakage and slippage during female and male condom use. Goal: The goal of this study was to determine condom breakage and slippage rate. Study: We conducted a 6-month prospective follow-up study of women attending 2 sexually transmitted disease clinics. Breakage and slippage rates were computed. Logistic regression was used to evaluate baseline characteristics and time-dependent behaviors. Results: A total of 869 women used condoms in 20,148 acts of intercourse. Breakage was less common for female condoms (0.1%; 95% confidence interval [CI], 0.05-0.21) than for male condoms (3.1%; 95% CI, 2.80-3.42). Slippage was more common for female condoms (5.6%; 95% CI, 5.10-6.13) than for male condoms (1.1%; 95% CI, 0.90-1.28). Rates significantly decreased with use and increased with number of previous failures. From first use to > 15 uses, combined failure rate fell from 20% to 1.2% for female condoms (P < 0.0001) and 9% to 2.3% for male condoms (P < 0.01). Conclusions: Both condoms may provide good protection against sexually transmitted diseases. Experience determines success with either condom.