This study evaluated the effectiveness of an ancillary service assignment protocol to improve women's retention in HIV medical care. HIV-positive women with acknowledged difficulty in keeping regularly scheduled HIV clinic appointments were assigned to an intervention based on presenting characteristics: 6 months transportation plus nursing case management followed by 6 months transportation only for women currently using heroin and/or showing mental illness problems or transportation only for 12 months. Self-report and HIV clinic data provided measures of kept and missed appointments. Results were as hypothesized. The Transportation Only sample maintained number of kept appointments and significantly decreased number of missed appointments. The Transportation Plus sample significantly increased number of appointments kept and significantly decreased number of missed appointments. When intensive intervention was reduced to transportation only, charted HIV medical appointments significantly decreased. Positive influence on retention in HIV medical care requires level of intervention to be determined by current relevant client characteristics.