Previous studies using multiple measures of retention in care have suggested a significant association of retention with health outcomes among HIV-positive patients. The current study aims to examine age differences in retention in care across three measures of retention among HIV-positive patients in South Carolina. The relevant data were requested from the Health Sciences South Carolina (HSSC) Clinical Data Warehouse (CDW). The study sample comprises 5,447 patients (age ≥ 12) who had their first outpatient visit between 2007 and 2015 and who were not decreased by data collection time. Measures included three retention measures (gaps in care, visit constancy, and HRSA proportion), demographics, insurance, year of first visit, and institution. Bivariate analyses and multivariate multiple regression were conducted to identify associations of age groups with retention in HIV care. Bivariate analyses indicated that retention in HIV care among adolescents and youths (12-24 years) and older patients (≥ 50 years) was higher than that among young (25-34 years) and middle-aged adults (35-49 years) across all three measures. Multiple regression analyses indicated that age differences in retention in HIV care could still be detected across measures of retention while other key socio-demographic variables were controlled for. The findings indicate that different measures of retention in HIV care can be used interchangeably, and interventions that can help improve retention in HIV care among young and middle-aged adults are needed.