An analysis of data from Cameroon and Nigeria reveals that infertility has declined among all age-groups younger than 40 in the decade between the World Fertility Surveys and the Demographic and Health Surveys. The expected number of infertile years between ages 20 and 39 declined from 7.3 to 6.0 in Cameroon and from 5.6 to 4.2 in Nigeria. In addition, the proportion of childless women declined from 12% to 6% in Cameroon and from 6% to 4% in Nigeria. Still, a substantial proportion of women suffer from infertility in both countries--39% of women aged 20-44 in Cameroon and 33% in Nigeria. The age pattern of infertility is similar in both countries, and the prevalence of infertility is associated with a woman's age at first sexual exposure. In Nigeria, for example, the proportion of women infertile at ages 20-24 reaches 15% among those who had intercourse before age 13, but is only 4% among those who postponed sexual activity until after their 19th birthday. Marked regional variations in infertility also exist in both countries. Despite the decline in infertility, the total fertility rate remained stable in Nigeria during the 1980s--at about 6.0 children per woman--while that in Cameroon fell from 6.4 to 5.8 children.