HIV testing and counseling is a critical component of HIV prevention efforts and core element of current "treatment as prevention" strategies. Mobility, low education and income, and limited access to health care put Latino migrants at higher risk for HIV and represent barriers for adequate levels of HIV testing in this population. We examined correlates of, and missed opportunities to increase, HIV testing for circular Mexican migrants in the U.S. We used data from a probability-based survey of returning Mexican migrants (N=1161) conducted in the border city of Tijuana, Mexico. We estimated last 12-months rates of HIV testing and the percentage of migrants who received other health care services or were detained in an immigration center, jail, or prison for 30 or more days in the U.S., but were not tested for HIV. Twenty-two percent of migrants received HIV testing in the last 12 months. In general, utilization of other health care services or detention for 30 or more days in the U.S. was a significant predictor of last 12-months HIV testing. Despite this association, we found evidence of missed opportunities to promote testing in healthcare and/or correctional or immigration detention centers. About 27.6% of migrants received other health care and/or were detained at least 30 days but not tested for HIV. Health care systems, jails and detention centers play an important role in increasing access to HIV testing among circular migrants, but there is room for improvement. Policies to offer opt-out, confidential HIV testing and counseling to Mexican migrants in these settings on a routine and ethical manner need to be designed and pilot tested. These policies could increase knowledge of HIV status, facilitate engagement in HIV treatment among a highly mobile population, and contribute to decrease incidence of HIV in the host and receiving communities.