PIP: In each of the nine regions of the Dominican Republic a sample of 300 girls was studied: 100 from private schools, 100 from public urban schools, and 100 from public rural schools, making a total of 2700 girls studied on a national scale. Age, menarche, region, and socioeconomic factors were investigated. Age at menarche was obtained by the Statu Quo method by interviewing the girls about the start of menstruation in groups and using the adjusted data in a logit curve for getting the average (the age when 50% had started menstruating). In the national sample, the age of menarche was 12-13 years, when 50% had started menstruating. The national average was 12.6 years. For the urban population, including private schools and urban public schools, the average was 12.5 years; while for the rural sample the average age of menarche was 13.1 years. Variations existed in different regions: in region I (Barahona) the age of menarche was 13-14 years; in region II (San Juan) it was 12-13 years; in region III (Azua) it was 12-13 years; in region IV (National District) it was 11-12 years; in region V (San Pedro Macoris) it was 12-13 years; in region VI (La Vega) it was 12-13 years; in region VII (San Francisco de Macoris) it was 13-14 years; in region VIII (Santiago) it was 12-13 years; and in region IX (Mao) it was 12-13 years.