This study examined sociodemographic variables, personality characteristics, and alcohol and drug misuse among male sex workers in the city of Santo Andre´, Sao Paulo, Brazil. A total of 45 male-to-female transgender sex workers and 41 male hustlers were evaluated in face-to-face interviews at their place of work from 2008 to 2010. A “snowball” sampling procedure was used to access this hard-to-reach population. Male-to- female transgender sex workers reported fewer conventional job opportunities, fewer school problems, and higher harm avoidance and depression levels than male hustlers. Also, transgender sex workers reported earning more money through sex work and more frequently living in hostels with peers than their counterparts. As biological male sex workers are a heterogeneous population, attempts to classify them into distinctive groups should be further carried out as a way to better understand and identify their behavior, design effective health interventions, and consequently minimize the likelihood of unintended adverse outcomes. Our study showed that gender performance can be an important variable to be considered by researchers and policy makers when working with sex workers and developing HIV/AIDS prevention and public health programs, given that transgender and male sex workers not only display distinctive behavior and physical appearance but also reveal differences on specific psychological measures, such as personality traits and depression levels. We recommend that counsellors working with this population strike a balance between facilitating self-disclosure and establishing more evidence-based directive interventions.