The purpose of the following secondary analysis was to examine the relationship between substance use and missed medical appointments among women living with HIV/AIDS (WLWHA). This study used an existing data set from the Coordinated HIV Assistance and Navigation for Growth and Empowerment for Women (CHANGE for Women) Program at Christie's Place. Christie's Place is a nonprofit social service organization that serves women, children, and families impacted by HIV/AIDS in San Diego County. The data set included 115 women whose information was collected from August 22, 2013 through May 31, 2015 as part of standard clinical care and service assessment conducted routinely by Christie's Place. The analysis applied descriptive statistics to describe the socio-demographic profile of the study population and explored indicator and outcome variables of interest. A logistic regression was conducted to examine the relationship between substance use and the outcome variable of missed HIV medical care appointments (yes/no). Bivariate results revealed drug and alcohol use to be significantly associated with missed medical appointments (p = 0.04). However, multivariable analysis showed no significant relationship between substance use and missed medical appointments among this sample population (p = 0.24). Although no significant relationship was found between substance use and missed medical appointments, analyses did reveal that services needed was significantly associated with missed medical appointments (p = 0.02). Although there have been numerous studies addressing medication adherence among WLWHA, few studies define adherence as missed medical appointments. Understanding the factors that can impact medical appointment adherence to HIV-medical care among WLWHA is critical to improving the services offered to this population, which can in turn improve patient health outcomes and overall quality of life. Continued research is needed for understanding how these factors are interrelated and the role substance use can play.