The age pattern of fertility in a rural area of South Africa under demographic surveillance (Agincourt subdistrict) was investigated over the 1992-97 period. The total fertility rate (TFR) averaged 3.3 births per woman of reproductive age over the period, a major drop from earlier estimates in the same area (6.0 births in 1970-74). Age-specific fertility rates showed an atypical bimodal pattern. They were decomposed into two components of similar magnitude: premarital fertility (among women aged 12-26) and marital fertility (among women aged 15-49). The decomposition revealed the two underlying modes: a mode of premarital fertility (among women aged 18-20) and a mode of marital fertility (among women aged 28-30). Premarital fertility accounted for 21 percent of all births and for 47 percent of births among women aged 12-26. This pattern of high premarital fertility appears to reflect a low incidence of contraceptive use before the first birth, especially among adolescents, a low prevalence of abortion, and a high contraceptive prevalence thereafter. This finding calls for a reorientation of the family planning policy, which until now has targeted married women and women who have been pregnant once, but has failed to address the contraceptive needs of young women before their first pregnancy, especially adolescents.