Few studies have sought to assess predictors of retention of racial/ethnic or sexual minorities in longitudinal health research. The purpose of this study is to investigate predictors of retention of Latino gay and bisexual men and transgender (GBT) research participants after the baseline interview. Data come from a sample of 643 Latino GBT individuals in two cities (Chicago and San Francisco). We assessed potential predictors of retention (operationalized as successful re-contact) using binary logistic regression of retention on five factors (sociodemographic/health, residential stability, acculturation/attachment to the United States, gay community attachment/stigmatization and research process/design). Our overall follow-up rate was 83 and 80% at 3 and 6 months, respectively. We found that traditional factors (e.g. education, income) were not associated with retention among Latino GBT. The strongest predictors of successful retention were the number of pieces of contact information provided by participants and city of residence (San Francisco). Furthermore, successful methods of contact (i.e. telephone, email) varied by city. We conclude that a largely immigrant urban population of Latino GBT individuals can be successfully followed in longitudinal research. The strong relationship between study design variables and successful retention indicates that collection of thorough contact information is vital to successful follow-up with this population. (Contains 4 tables.)