Equitable health service utilization is key to health systems' optimal performance and universal health coverage. The evidence shows that men and women use health services differently. However, currentanalyses have failed to explore these differences in depth and investigate how such gender disparities vary by service type. This study examined the gender gap in the use of outpatient health services by Mexican adults with non-communicable diseases (NCDs) from 2006 to 2022. A cross-sectional population-based analysis of data drawn from National Health and Nutrition Surveysof 2006, 2011-12, 2020, 2021, and 2022 was performed. Information was gathered from 300,878 Mexican adults aged 20years and older who either had some form of public health insurance or were uninsured. We assessed the use of outpatient health services provided by qualified personnel for adults who reported having experienced an NCD and seeking outpatient care in the 2 weeks before the survey. Outpatient service utilization was disaggregated into four categories: non-use, use of public health services from providers not corresponding to the user's health insurance, use of public health services from providers not corresponding to the user's health insurance, and use of private services. This study reported the mean percentages (with 95% confidence intervals [95% CIs]) for each sociodemographic covariate associated with service utilization, disaggregated by gender. The percentages were reported for each survey year, the entirestudyperiod, the types of serviceuse, and the reasons for non-use, according to the type of health problem. The gender gap in healthservice utilization was calculated using predictive margins by gender, type of disease, and survey year, and adjusted through a multinomial logistic regression model. Overall, we found that women were less likely to fall within the "non-use" category than men during the entire studyperiod (21.8% vs. 27.8%, P < 0.001). However, when taking into account the estimated gender gap measured by incremental probability and comparing health needs caused by NCDs against other conditions,compared with women, men had a 7.4% lower incremental likelihood of falling within the non-use category (P < 0.001), were 10.8% more likely to use services from providers corresponding to their health insurance (P < 0.001), and showed a 12% lower incremental probability of using private services (P < 0.001). Except for the gap in privateservice utilization, which tended to shrink, the others remained stable throughout the period analyzed. Over 16years of outpatient service utilization by Mexican adults requiring care for NCDs has been characterized by the existence of gender inequalities. Women are more likely either not to receive care or resort to using private outpatient services, often resulting in catastrophic out-of-pocket expenses for them and their families. Such inequalities are exacerbated by the segmented structure of the Mexican health system, which provides health insurance conditional on formal employment participation. These findings should be considered as a key factor in reorienting NCD health policies and programs from a gender perspective.