Population aging has a direct impact on the increasing demand of health services and on medical care costs. The objective was to carry out a cost analysis of health care costs in older adults in a regional general hospital of the Instituto Mexicano del Seguro Social. A calculation of the costs was done based on a retrospective collection of health care data. Unit prices were used to estimate costs. These were reported in 2016 Mexican pesos. A cost analysis was carried out by means of a regression model. Explanatory variables were sex, age and comorbidity level, the latter measured by using the Charlson index. The average cost of all the 509 patients was 34 769 Mexican pesos (SD = 2869 pesos). Age variable explains the costs; however, sex and comorbidity variables were not significant. Cost predictions with the statistical model show differences mainly by age. In the case of females, the model predicts greater costs compared with those of males. Costs for older adults of 85 years or more were greater than those for the group of younger people (75-84). The hospitalization costs estimated are high and they differ according to the age group. We suggest to make further research in order to know the factors associated with high hospital costs for this age group.