Purpose – The purpose of this paper is to examine sex differences in mental health service usage among upper-middle, lower-middle, and low-income countries (LICs). Design/methodology/approach – Data from 62 low- and middle-income countries (LAMICs) were collected with the World Health Organization – Assessment Instrument for Mental Health Systems (WHO-AIMS). Sex differences in mental health service utilization were assessed by comparing the proportion female in the general population with the proportion female treated for mental illness in five different types of mental health facility. Findings – Two-sided t-tests for significance (a=0.05) revealed a significant difference between the proportion female in the population and the proportion treated in inpatient facilities (community-based and mental hospitals) in LICs. There was also a trend toward decreased use of outpatient facilities by women in LICs (p=0.08). Lower-middle and upper-middle income countries showed no differences. In day treatment facilities for the entire sample, there was a significant difference between the proportion female in the population and the proportion treated female (weighted mean difference overall=0.10, p=0.035). Research limitations/implications – The authors found significantly reduced utilization of mental health services by women in LICs in community-based inpatient facilities and mental hospitals and a trend toward decreased use in outpatient facilities. Future studies investigating the factors contributing to the lower utilization of services by women in LICs are essential. Originality/value – This study presents the first comprehensive study of mental health service usage by sex in 62 LAMICs.