Men's decisions and behaviours influence the sexual, reproductive and maternal health of women and the health of their families, but men are rarely included in reproductive and maternal health care services. Men's attendance at antenatal care has the potential to prevent women from becoming infected with HIV during pregnancy and post-partum, when they are more vulnerable to infection and have a high risk of transmission to the infant. Greater involvement of men requires an understanding of social, cultural and organisational barriers in different contexts. In 2006, the Burnet Institute undertook fieldwork to inform a pilot project to encourage expectant fathers to attend antenatal care. A local Lao team conducted focus group discussions and interviews in Vientiane with expectant fathers, pregnant women, older women and health care providers. It was found that myths about the dangers of sex during pregnancy and women's decreased desire resulted in periods of sexual abstinence. Participants reported that unprotected extramarital sex was common but difficult for couples to discuss. Men lacked knowledge about sexually transmitted infections, including HIV. Men wanted information so they could better protect the health of their partners and babies during and after pregnancy, and reported being willing to attend antenatal care when invited. Our findings have useful implications for policy and implementation.