Abstract Objectives: Age at menarche (MA) is a proxy for biological maturation and a parameter of socioeconomic changes. Worldwide, anticipation of menarche is associated with nutritional transition and excess weight. The objective of this study was to evaluate the MA in Amazonian students and its association with nutritional status, ethnicity, and socioeconomic level. Methods: Cross-sectional study with 1,017 students aged 6 to 17 living in the city of Manaus, Brazil. MA was analyzed by status quo and recall; its association with body mass index (BMI), race, socioeconomic status, and adult height was examined. Results: 559 (51.9%) participants had already experienced menarche. In 91.7%, menarche occurred between 10 and 14 years of age; the mean age at the onset of menarche was 11.9 years. Overweight (11.6 years) and obese (11.4 years) participants reached menarche earlier than those with normal weight (12 years) and lean (12.7 years) participants. The associations between MA and nutritional status showed that overweight and obesity are risk factors for the early occurrence of menarche. MA was not associated with socioeconomic status/parental education or race. However, excess weight was associated with earlier MA in all races and social classes. The adult height was slightly lower in girls with menarche before 12 years old (157.9 vs 159.4 cm). Conclusion: Regardless of socioeconomic level or ethnicity, excess weight was associated with earlier menarche in Amazonian students. Objectives (MA changes Worldwide ethnicity Methods Crosssectional Cross sectional 1017 1 017 1,01 Manaus Brazil recall BMI, BMI , (BMI) race examined Results 55 51.9% 519 51 9 (51.9% 917 91 7 91.7% 119 11 11. 11.6 116 (11. 11.4 114 4 (1 12.7 127 (12. statusparental parental However classes 157.9 1579 157 (157. 1594 159 159. cm. cm . cm) Conclusion 101 01 1,0 (BMI 5 51.9 (51.9 91.7 (11 ( 12. 157. 15 (157 0 1, 51. (51. 91. (15 (51 (5