Early onset (< age 40 years) psoriasis has been reported to be more readily triggered by environmental factors such as stress, in contrast to late onset (> or = age 40 years) psoriasis. We examined whether certain psychopathologic factors differentiated the psoriasis patient with early onset versus late onset disease. One hundred and thirty-seven psoriasis inpatients completed a battery of psychosocial questionnaires. Logistics regression analysis, using the psychologic measures, age and TBSA affected as independent variables, revealed that higher Anger-in (Anger Expression Scale) scores significantly (p < 0.05) increased the odds or probability of having early versus late onset psoriasis. Psoriasis with onset prior to age 40 is comorbid with greater difficulties with assertion and expression of anger, a personality trait that may adversely affect the patient's capacity to cope with stress.