Objective To examine stigmatizing attitudes towards people with mental disorders among primary care professionals and to identify potential factors related to stigmatizing attitudes through a systematic review. Methods A systematic literature search was conducted in Medline, Lilacs, IBECS, Index Psicologia, CUMED, MedCarib, Sec. Est. Saúde SP, WHOLIS, Hanseníase, LIS-Localizador de Informação em Saúde, PAHO, CVSO-Regional, and Latindex, through the Virtual Health Library portal ( http://www.bireme.br website) through to June 2017. The articles included in the review were summarized through a narrative synthesis. Results After applying eligibility criteria, 11 articles, out of 19.109 references identified, were included in the review. Primary care physicians do present stigmatizing attitudes towards patients with mental disorders and show more negative attitudes towards patients with schizophrenia than towards those with depression. Older and more experience doctors have more stigmatizing attitudes towards people with mental illness compared with younger and less-experienced doctors. Health-care providers who endorse more stigmatizing attitudes towards mental illness were likely to be more pessimistic about the patient’s adherence to treatment. Conclusions Stigmatizing attitudes towards people with mental disorders are common among physicians in primary care settings, particularly among older and more experienced doctors. Stigmatizing attitudes can act as an important barrier for patients to receive the treatment they need. The primary care physicians feel they need better preparation, training, and information to deal with and to treat mental illness, such as a user friendly and pragmatic classification system that addresses the high prevalence of mental disorders in primary care and community settings.