We investigated the relationship between autistic-like traits in early childhood and age at menarche in typically developing girls. Autistic-like symptoms were measured at age 2 years using the Child Behaviour Checklist, and age at menarche (AAM) was determined prospectively using self-report questionnaires at age 8, 10, 14 and 17 years. Girls with "high" autistic-like symptoms at age 2 years demonstrated significantly later AAM (n = 70; M = 13.07 years; SD = 1 year) than girls reported to show "typical" (n = 216; M = 12.72 years; SD = 1.1) or "low" (n = 47; M = 12.66 years; SD = 1.13 years) levels of these behaviors. These data further establish a link between the autism phenotype and later AAM and may provide insights into the etiology of the condition.