Since 1987, the Gambia National Cancer Registry has provided nationwide cancer registration for the Gambia. We used data from 1998 to 2006 to assess age-standardized incidence rates (ASRs) of 2 common cancers in women, breast and cervix. With an ASR of 15.42 (95% CI [14.18–16.66]) for cervix and 5.86 (95% CI [5.12–6.59]) for breast per 105 person-years, these cancers ranked first and third, respectively, among Gambian women (the second most common being liver, ASR 14.90). Incidence of both cancers, breast and cervix, increased rapidly at young ages to reach a peak at ages 40–44 years. Significant differences were observed in relation to ethnicity. Using the Mandinka (42% of the population) as a reference, breast cancer incidence rates were 2.16-fold higher (95% CI [1.33–3.52]) in Jola (10% of the population), specially at early-onset ages (before 40 years). For cervix cancer, highest rates were observed in Fula (18% of the population; risk ratio (RR): 1.84 (95% CI [1.44–2.36])). In contrast, a significantly lower risk was observed in the Serrahuleh (9% of the population; RR: 0.54 (95% CI [0.31–0.96]). This study revealed a preponderance of early-onset breast cancer among Gambian women similar to that seen in African women in more developed countries but also demonstrates large ethnic variations. It points to the need for further studies on cancer determinants to improve prevention, early detection and therapeutic management of these diseases in a low-resource setting in West Africa.