We characterized patients at publicly funded HIV/AIDS patient treatment sites who moved ("migrated") post-diagnosis of HIV to five urban Florida counties, by geographic, demographic, socioeconomic and risk variables. Each patient who came for services at the sites in a 2-3 week sampling period was asked to complete a brief, self-administered questionnaire. We compared migrant with non-migrant patients to disclose characteristics predictive of migration and help plan for continuity of HIV care, future funding, and HIV prevention. Overall, 25% (range by site, 20%-38%) of the 1,286 patients in the study migrated to the counties from a non-contiguous Florida county, another state, or another country. In a multivariate model comparing interstate migrants with non-migrants, white and Hispanic race/ethnicity, age 9-29 years at first HIV diagnosis compared with older age, increasing education, highest current income and exposure category (men having sex with men and injection drug users) were independently associated with migration (all p < 0.05). In a similar model for international migrants, the independently associated variables included Hispanic ethnicity, education, and younger age at first HIV diagnosis. Although migrating can bring benefits to a patient such as improved access to health care or a new employment opportunity, it is stressful because it can result in changes in a person's social network, employment, and health care providers. Thus, moving could create unique patient needs concerning medication adherence, risk-taking, and other psychosocial needs. Given the high percentage of migrants in these urban Florida county clinics, these needs should be further examined and addressed.