Objective: To understand the changes in syphilis serology after regular treatment. Methods: Patients with clinical evidence and credible medical history of syphilis were treated regularly. Their serologic tests were followed for two years. Results: At the end of half a yea 22.95% of patients had a negative USR but 26.23% remained positive even after 2 years. More than 3% of patients had a negative FTA-ABS result. These patients tended to be under 40 with a disease course of less than 2 years. Conclusion: The resolution rate was high for patients who were young, had a shorter course of disease and reacted strongly to the infection. In patients older than 40 with a long course of disease, the resolution rate was low.