Objectives:To estimate age at menarche and to assess trends in menarcheal age among Saudi women.Methods:A prospective longitudinal study was conducted among healthy prepubertal female school children and adolescents from September 2006 to July 2012 in Riyadh, Kingdom of Saudi Arabia. Study participants were invited from diverse socioeconomic backgrounds. Tanner stage, height, weight, body mass index, and socioeconomic parameters including parent’s level of education were collected. Age at menarche was compared with maternal age at menarche.Results:The study included 265 girls and mothers. Mean±standard deviation (SD) age at menarche for girls was 13.08 ± 1.1 years, and their distribution category across the ≤10 years was 4 (1.5%), 11-14 years was 239 (90.2%), and ≥15 years was 22 (8.3%) girls. Anthropometric measurements, mother’s level of education, and family income were not statistically significant determining factors associated with age at menarche. Mean ± SD age at menarche for mothers was 13.67 ± 1.4 years, and their distribution category across the ≤10 years was 7 (2.6%), 11-14 years was 172 (64.9%), and ≥15 years was 86 (32.5%). Girls attained menarche at younger age compared with their mothers (p<0.0001). A downward secular trend in age of menarche was observed (Cuzick test for trend = 0.049).Conclusion:Saudi girls attain menarcheal age earlier than their mothers, reflecting a downward secular trend in menarcheal age.