Background: Syphilis increases the risk of HIV transmission. Coinfection of both infectious diseases potentially changes the presentation of mucocutaneous lesions and accelerates disease progression, complicating the diagnosis and treatment with standard regimens. In the case study, we present a case of secondary syphilis in an HIV-positive patient with clinical manifestations resembling mid-borderline leprosy. Case presentation: A 23-year-old male patient was referred to the emergency care unit of Dr. Soetomo General Hospital with red spots on the palms of the hands and soles of the feet for the past four months. The skin manifestation first appeared as a single spot, grew over time with itch and pain. The patient had lost 15 kg of body weight in the last three months which was confirmed as HIV-positive. He was also treated for leprosy based on the skin manifestations ever since. There was no history of direct contact with leprosy patients. The patient admitted that he had sex with men in the last 3-4 years. The laboratory examination showed negative results for Mycobacterium leprae through skin biopsy and negative for IgM and IgG of anti-phenolic glycolipid-1 (PGL-1). The patient however was positive for syphilis due to high titers of venereal disease research laboratory/rapid plasma regain (VDRL/RPR) and treponema pallidum hemagglutination (TPHA), supported by histological findings. The patient’s condition improved after receiving penicillin benzathine G, the definitive treatment for syphilis. Conclusion: Secondary syphilis is a great imitator to mid-borderline leprosy, especially in HIV patients. To avoid misdiagnosis and mistreatment, a careful physical and laboratory examination, including serology and histopathology, should be carried out.