Psoriasis is associated with considerable physical and psychological morbidity. Optimal use of psoriasis treatments can limit the physical manifestations of psoriasis and help improve quality of life, but nonadherence is common. Smoking, obesity and excessive alcohol consumption are prevalent in this population. A systematic review of adherence to medication and recommendations for lifestyle change in psoriasis was undertaken, with a critical appraisal of the quality of the selected studies. Electronic searches from inception to March 2012 (PubMed, Web of Science and Embase) were conducted. Twenty-nine studies were included; however, none examined adherence to advice about lifestyle change. Studies using a dichotomous classification of adherence tended to report suboptimal adherence, with 21·6–66·6% of patients classed as adherent. No consistent pattern of results emerged for sociodemographical, disease and lifestyle factors as determinants of adherence. However, some treatment factors were associated with adherence. While mixed findings were reported for quality of life as a determinant of adherence, psychological factors (psychological distress and patient satisfaction with care and therapy) were associated with adherence. Only tentative conclusions can be made for determinants of adherence because the methodological quality of many of the included studies limits conclusions. There is a need for improved quality of research and reporting in this area, and this review provides a platform from which future research within this area should progress, along with suggested research recommendations.