Malignant syphilis is an uncommon manifestation of secondary syphilis, in which pleomorphic pustules, nodules, and ulcers may be associated with systemic signs and symptoms. It is frequently associated with HIV co-infected patients. Malnutrition, abusive consumption of alcohol and concomitant debilitating illnesses are other possible predisposing factors. We describe herein a rare case of malignant syphilis occurred in an immunocompetent patient. A 58-year-old man with diabetes mellitus presented with a one-month history of ulcerative nodules on the entire body. Physical examination revealed multiple, variable-sized, erythematous nodules with central crusted ulcers over the entire body. He had been suffering fever and myalgia for seven days. The histopathologic examination revealed an acanthotic epidermis, and dense lichenoid lymphohistiocytic infiltrate rich in plasmocytes in the dermis. Laboratory investigations including complete blood count, blood chemistry, hepatitis B and C markers, and HIV serology were unremarkable. But, syphilis serology test demonstrated positive treponemal test and a TPHA titer of 1:640. Based on the histopathologic and laboratory findings, the diagnosis of malignant syphilis was made. The patient was treated with intramuscular 2.4 million units of benzathine penicillin once weekly for three weeks. After treatment, the lesions showed complete resolution.