Introduction: Syphilis is an ancient disease that has caused great damage throughout the history of humanity and, despite sexual protection methods and antibiotics to combat this infection, its prevalen- ce is still alarming today. The dentist plays an essential role in this field because he must be trained to early detect the manifestations of the disease in the oral cavity, which would prevent its progression.   Materials and methods: A cross-sectional, descriptive study was conducted, with 20 patients who consulted three stomatology services in South America; a stomatological examination was done and an exhaustive clinical history was obtained; the lesions found were classified and the other data collected were analyzed.   Results: The lesion prevalent in primary syphilis was ulcers and only one case was detected; about the secondary form, nineteen cases were detected, and multiple associated lesions were found; finally, no case of tertiary syphilis was found.   Conclusions: Disclosure of these results and further research in this field are considered essential to educate and thus prevent the progression of syphilis to a latent or tertiary form that endangers the life of the population.