A 57-year-old male, with no significant medical history, presented with asymptomatic erythematous patches and pustules on whole body for 10 days. He had myalgia, chilling and fever over 39 degrees. He went to the mountain 4 weeks before the symptoms, and the season was autumn. The full blood count yielded leukocytosis with predominance of neutrophils and increase of alkaline phosphatase(ALP), gamma-glutamyl transferase(γ-GTP), lactate dehydrogenase(LDH), and C-reactive protein(CRP). Histopathologic examination showed endothelial swelling, dermis with neutrophils and leukocytoclasia. The followed serological test, leptospiraantibody was positive. The patient was diagnosed Sweet’s syndrome with leptospirosis. He was discharged well after steroid and antibiotics therapy with no sequelae. Sweet’s syndrome is an acute reactive disorder characterized by the abrupt onset of skin lesions, dense infiltration of neutrophils in the dermis and associated systemic features such as fever, leukocytosis and increase of CRP. Infections have been occasionally associated with Sweet’s syndrome. Leptospirosis is a spirochetal zoonosis worldwide in distribution that causes clinical illness in human. It may have triggered the innate immune system which then cytokines resulting the immunological cascade contributing to Sweet’s syndrome. Here, we are reporting a rare case of Sweet’s syndrome associated with leptospirosis.