Pustulosis palmaris et plantaris (PPP) and pustulotic arthro‐osteitis (PAO) are tonsil‐related diseases. Treatment outcome of tonsillectomy and prognostic factors influencing the outcome have not been analyzed quantitatively. We evaluated those using the Palmoplantar Pustulosis Area and Severity Index (PPPASI). At 1, 3, 6, 12, 24 and more than 24 months post‐tonsillectomy, 20 (31%), 34 (48%), 70 (60%), 57 (80%), 36 (95%) and 23 (96%) patients realized 80% or more improvement of PPP skin lesions, respectively, and eight (17%), 23 (36%), 30 (50%), 38 (79%), 12 (100%) and four (100%) patients showed 80% or more improvement of PPPASI (i.e. PPPASI% ≥ 80%), respectively. At 1, 3, 6, 12 and more than 12 months post‐tonsillectomy, 19 (73%), 21 (66%), 27 (73%), 19 (79%) and 15 (83%) patients realized a disappearance of PAO‐induced arthralgia, respectively. Kaplan–Meier analysis of 80 patients with PPP revealed that, at 12 and 24 months post‐tonsillectomy, lesions disappeared (i.e. PPPASI = 0) in 38% and 66% of patients, respectively, and lesions improved by 80% or more (i.e. PPPASI% ≥ 80%) in 71% and 95% of patients, respectively. The log–rank test and univariate and multivariate analyses showed that smoking cessation post‐tonsillectomy and PAO were significant predictive factors for the early disappearance of skin lesions. This report is the first demonstrating objective evidence of the great efficacy of tonsillectomy to improve PPP skin lesions. Even post‐tonsillectomy, smoking inhibited the early disappearance of the lesions.