BACKGROUND There is a paucity of information on the prevalence and severity of acne of the face, chest, and back. PURPOSE This study was designed to examine the prevalence and severity of acne on the face, chest, and back in a referral cohort of patients with acne using a validated global acne severity scale. METHODS Acne patients referred to dermatologists were evaluated at the face, chest, and back. Chi-square testing was performed to assess consistency between patient and physician assessments of each region. The correlation of acne severity between regions was evaluated by Spearman's rank correlation. RESULTS In 965 patients, the prevalence of acne on the face, chest, and back was 92%, 45%, and 61%, respectively. Acne severity was significantly correlated for all regional pairs (P<.001): face and back (r=0.11); face and chest (r=0.12); and chest and back (r=0.67). The consistency of patient reporting and clinical evaluation for the presence of acne varied by region: face=92%, chest=69%, and back=74%. The proportions of patients reporting no occurrence of acne when clinical acne was indeed absent (negative predictive value) were 67% and 65% for the chest and back, respectively. LIMITATIONS The operational threshold for clinical acne (>mild) may underestimate the total proportion of affected patients. These patients were referred to dermatologists for care and may represent a more severe cohort. CONCLUSION Acne affected the face in 92% and the trunk in just over 60% (with the back more frequently and severely affected than the chest). Acne severity was observed to have a much higher correlation between chest and back than face and back or face and chest. Patient-reporting evaluations of absence of acne on the chest and back are frequently erroneous, mandating clinical evaluations of these sites for assessment of overall extent.