Introduction: Syphilis is one of the oldest sexually transmitted diseases caused by the bacterium Treponema pallidum. It is characterized by multiple clinical presentations and a long duration. Acquired syphilis is divided into early (≤ 1 year after infection) and late ( > 1 year after infection) stages. Venereal diseases, more often defined as sexually transmitted diseases (STDs), result from behaviours influenced by socio-economic, psychological, and cultural factors. Although the spectrum of sexually transmitted diseases, apart from classic syphilis and gonorrhoea, encompasses a wide range of aerobic and anaerobic bacteria, viruses, protozoans, fungi, and even insects, the frequency of late syphilis has been on the rise in recent years. It is a significant clinical problem in our country. Irrespective of the COVID SARS-19 pandemic, this is an important issue of contemporary epidemiology. Objectives: The objective of this study was to present two cases of women diagnosed with acquired late syphilis of unknown duration, treated at the Department and Clinic of Dermatology at the Poznań University of Medical Sciences.  Material and methods: CASE 1 — A 72-year-old female patient was admitted to the Clinic of Dermatology with late latent syphilis of unknown duration. The results of laboratory tests showed: a positive syphilis reaction: FTA-ABS 1:100, TPHA — 1:160. One dose of 2.4 million units of intramuscular benzathine penicillin was administered. It was recommended to administer the second dose of 2.4 million units of benzathine penicillin within 7 days of the first dose. CASE 2 — A 29-year-old female patient was admitted to the Department and Clinic of Dermatology at the Poznań University of Medical Sciences with late latent syphilis of unknown duration. A primary lesion on the right labium major, regional lymphadenopathy, and a rash on the right side of the chest were observed. The results of laboratory tests showed: qualitative TPHA test — positive, quantitative TPHA test — positive (titre 1:180), RPR — positive (RPR – titre 1:1). Conclusions: In recent years, the incidence of late syphilis has been on the rise globally. This disease has again become a significant clinical issue requiring particular attention in dermatological and venereological practice. When syphilis is diagnosed, adequate treatment is necessary in accordance with the updated EADV guidelines.