The objective was to evaluate the impact of additional lubricant on condom breakage and slippage. Two hundred and sixty-eight couples used 6 new and 6 aged condoms during vaginal intercourse and were instructed to use 2 of each type with either water-based lubricant, oil-based lubricant or no additional lubricant. The use of either oil-based or water-based lubricant increased slippage rates of new and aged condoms, although only one pairwise comparison (oil-based lubricant vs. no additional lubricant) was statistically significant (8.5% vs. 3.8%, P = 0.004). The use of oil-based lubricant increased breakage, although not statistically significantly, in both new and aged condoms. Water-based lubricant did not impact the breakage rate of the new condoms and decreased the breakage rate of the aged condoms (no additional lubricant 4.5% vs. water-based lubricant 2.1%, P = 0.029). From a functional perspective, this study suggests that condom users should be told not to use oil-based lubricants. The negative impact of water-based lubricant on slippage may be outweighted by the protective influence on breakage, especially for aged condoms. Over three-quarters of the couples (76%) had at least some incorrect knowledge, according to current condom instructions, of the type of lubricant that should be used with condoms.