To evaluate gender differences among children diagnosed with intermittent exotropia.Retrospective, population-based cohort study.The medical records of all Olmsted County, Minnesota residents younger than 19 years diagnosed with intermittent exotropia from January 1, 1975, through December 31, 1994, were reviewed.One hundred eighteen (64.1%) of the 184 study patients were girls with an age-adjusted incidence rate of 38.3 (95% CI: 31.4-45.2) per 100,000 compared to 20.8 (95% CI: 15.7-25.8) per 100,000 for boys (P < .0001). There were no significant differences between girls and boys in their family history of strabismus, birth weight, prevalence of prematurity, age at diagnosis and surgery, refractive error, and initial angle of deviation.Intermittent exotropia was nearly twice as common in girls compared with boys in this defined population. There were, however, no significant historical or clinical differences between the genders.