The effects of barrier and spermicidal methods of contraception on cervical cancer risk were examined by studying 479 cases of histologically confirmed invasive cervical cancer cases and 788 random digit dialing controls. In addition to a detailed history of contraceptive practices, information was available on numerous potential confounders, including demographic characteristics, sexual behavior, reproductive factors, Pap smear screening history, and smoking. After adjustment for relevant confounders, diaphragm and condom use were found not to be significantly associated with risk of cervical cancer. Although there was a small reduction in risk (OR = 0.8) associated with long-term use (5+ years) of the diaphragm, the effect appeared to relate to concomitant spermicide use, since there was evidence of further decreases in risk for women using spermicides alone for extended periods (OR = 0.7 for 5+ years). Effects were only seen among subjects of higher income and education levels, suggesting that patterns of usage may be important. The potential ability of spermicides to reduce cervical cancer risk by neutralizing viral agents warrants further attention. (Epidemiology 1990; 1:266–272)