We study how considerations of male circumcision as both a favourable practice and as protective against HIV are linked with ethnicity in sub-Saharan Africa, where many ethnic groups do not traditionally circumcise. We focus on Malawi, a country with a high HIV prevalence but low male circumcision prevalence. Survey data from a population-based random sample in rural Malawi (N=3400) was analysed for ethnoregional patterns in attitudes toward male circumcision. We used logit regression models to measure how reported circumcision status, region of residence, and ethnic identity relate to attitudes toward circumcision. Overall, Malawians reported more negative than positive opinions about male circumcision, but attitudes toward circumcision varied by ethnicity and region. The implications for agencies and governments aggressively scaling up the provision of male circumcision are clear: acceptance of circumcision as a tool for HIV prevention could be low in societies divided by ethnoregional identities that also shape the practice of circumcision.