The aim of this work is to analyse the socio-economic associated inequity in the use of health care services among older adults in Montevideo, capital city of Uruguay, based on data from the SABE survey in the years 1999-2000. We impute the equivalent household income through the use of the ECH (Household Continuous Survey) of the Statistics National Institute (INE). Considering a wide range of access, quality, and use of health care services indicators, we attempt to reduce the probable biases that arise from the fact that morbidity and use of health care services variables are measured contemporaneously. Also, we correct for the potential endogeneity of income and health by the use of Instrumental Variables. After the standardization of the use of services by necessity, we find horizontal inequity favouring the older adults with a higher socio-economic level, in the quality of access to the medical consultation (time to arrival and time to being attended), in the probability of having had a consultation in the last four and twelve months, and in the use of preventive services (mammography, Papanicolau, and prostate examination). The latter, show the higher levels of inequity. Through the Instrumental Variable analysis we deduce that inequity would be underestimated if endogeneity is not corrected for.