The aim of this study was to assess the impact of diabetes mellitus, Crohn’s disease, HIV/aids, and obesity on the prevalence and readmission rate of perianal abscess. The study cohort was based on the Swedish National Patient Register and included all patients treated for perianal abscess in Sweden 1997–2009. The prevalence and risk for readmission were assessed in association with four comorbidity diagnoses: diabetes mellitus, Crohn’s disease, HIV, and/or AIDS and obesity. A total of 18,877 patients were admitted during the study period including 11,138 men and 4557 women (2.4:1). Crohn’s disease, diabetes, and obesity were associated with a significantly higher prevalence of perianal abscess than an age- and gender-matched background population (p