We compare attitudes, experiences of learning about sex and first intercourse among Indians (n = 393) and Pakistanis (n = 365) using a probability survey of Britain's general population aged 16-44 years conducted during 1999-2001 (n = 12,110). Higher proportions of Pakistanis (64.6%) and Indians (28.1%) reported religion as 'very important' versus 6.2% of other ethnicities. Pakistanis were more conservative in their attitudes, e.g. reporting premarital sex as wrong (adjusted odds ratios [AORs] for sociodemographic differences, 4.71 [men] and 6.59 [women]). Pakistanis were more likely to be married at first sex (AORs 6.2 [men] and 9.53 [women]), yet men were more likely than women to be in non-marital relationships at this time (69.4% versus 25.2%). Pakistani men and women and Indian women were more likely to report not using reliable contraception at first sex relative to others (AORs 2.33, 3.16 and 1.90, respectively). Pakistani and Indian women were more likely than others to report school lessons as their main source of sex education (AORs 2.23 and 1.77) and not discussing sex with their parents during adolescence (AORs 2.04 and 2.62). These unique data have implications for ensuring that sex and relationship education and health promotion messages are appropriately planned, targeted and delivered to benefit Pakistanis and Indians.