Objective Establishing the factors associated with using healthcare for the aged in Cartagena, Colombia. Methods This was a cross-sectional study. A 656 sample-size was estimated for a population of 66,795 senior citizens; stratified sampling was used. A questionnaire entitled Using healthcare services (Uso de los servicios de salud) was used; descriptive statistics and logistical regression were then used for modeling the probability of being a healthcare service user. Results 656 senior citizens participated in the study; average age was 67.9 years old. 407 of the participants had consulted for disease during the last month (62.0 %); 376 of them (92.4 %) had consulted once or twice. Living in socio-economicstrata4, 5 and/or 6 (Chi2 4.14; p=0.043), having a diagnosed disease (Chi2 3.82 p=0,051), suffering from a chronic disease (Chi2 7.0; p=0.008) or waiting for 30 minutes or less to be seen (Chi2 3.17; p=0.075) were factors associated with using primary healthcare by senior citizens in Cartagena. Having a diagnosed disease (Chi2 3.59; p=0.0581) and waiting for 30 minutes or less to be seen (Chi2 3.02; p=0.0818) were the regression model variables explaining healthcare service use. Conclusion A senior citizen using primary healthcare in Cartagena was influenced by variables such as residing in mid-level socio-economic strata, having a diagnosed disease, suffering from a chronic disease and waiting for 30 minutes or less to be seen.