The use of condoms has assumed a central position in the current strategy to prevent sexual transmission of the human immunodeficiency virus. The effectiveness of condoms in disease prophylaxis is dependent, to a degree, on their correct use. Condom manufacturers routinely include information on condom use either printed on the actual package or in an enclosed package insert. With the use of three readability formulas, the reading grade level was determined for 14 different sets of instructions included with 25 brands of condoms manufactured by 7 domestic and 1 overseas manufacturer. The readability formulas, when applied to instructions for condom use, estimated that, conservatively, 8 of the 14 instructions required at least reading at the level of a high school graduate and none required less than a 10th grade level. Clearly written instructions and simple concepts could assist current and future condom users in the correct use of condoms and improve the effectiveness of condoms in the prevention of AIDS and other sexually transmitted diseases.