BACKGROUND: Gender plays a well-recognized role in shaping health inequities. However, the population-level health consequences of gender inequalities have not been measured comprehensively. The goal of this study was to evaluate the association between gender inequality and health indicators in organization for Economic Co-operation and Development (OECD) countries. METHODS: Ecological study based on 1990-2017 panel data for OECD member countries. Gender inequality was measured using the Gender Inequality Index (GII). The population health parameters evaluated were life expectancy (LE), healthy life expectancy (HALE), years of life lost (YLL), years lived with disability (YLD), disability-adjusted life years (DALYs), and specific-cause mortality. Two-way fixed-effects linear models were used to assess the relationship between gender inequality and health outcomes. Models included potential mediating and confounding factors such as health spending, political model, and income inequalities. FINDINGS: Greater gender inequality was associated with lower LE (-0·49%; CI95 -0·63%- -0·31%; p-value < 0·0001), HALE (-0·47%; CI95 -0·63%- -0·31%; p-value < 0·0001) and with increased premature mortality YLL (6·82%; CI95 3·63%-10·75%; p-value < 0·0001) and morbidity measured in DALYs (1·50%; CI95 0·48%-2·46%; p-value = 0·0028) and YLD (2·59%; CI95 0·67%-4·77%; p-value = 0·0063) for each 0·1 increments on the GII. The sensitivity analysis indicated that the results were robust to the various specifications of the causal models. INTERPRETATION: Our results suggest that gender inequality pose a sizable impact on population health outcomes. Promoting gender equality as part of public policies is vital for optimizing health on a population scale. FUNDING: Agencia Nacional de Investigación y Desarrollo (ANID)/Programa Becas/Magister Becas Chile/2017- 22,170,332.