Psychosocial evaluation is recommended prior to bariatric surgery. Practice guidelines have been published on assessment methods for bariatric surgery candidates, but they have not emphasized ethical issues with this population. This review outlines ethical and professional considerations for behavioral healthcare providers who conduct pre-surgical assessments of bariatric surgery candidates by merging ethical principles for mental health professionals with current practices in pre-surgical assessments. Issues discussed include the following: (a) establishing and maintaining competence, (b) obtaining informed consent, (c) respecting confidentiality, (d) avoiding bias and discrimination, (e) avoiding and addressing dual roles, (f) selecting and using psychological tests, and (g) acknowledging limitations of psychosocial assessments.