Introduction and aim: Genital wart infection is a distressing sexually transmitted infection that causes marked fear and stress to both males and females. Tuberculin Purified protein derivative (PPD) injection is an upcoming safe and effective modality for the treatment of genital warts. Interleukin 17 (IL-17) was found to be lower in wart patients than controls. This study aimed at measurement of serum level of IL-17 in genital warts patients before and after PPD injection. Patients and methods: The study was carried out as case-control interventional study on 63 patients (37 males and 26 females) with genital warts attending Dermatology and Andrology Clinics, faculty of medicine, Suez Canal University hospitals. 50 controls were enrolled in the study. All patients have injected 10 tuberculin units of PPD intradermally in the mother or largest warts every 2 weeks till 6 sessions. Serum level of IL-17 was measured by Sandwich ELISA technique to all patients before and after PPD injection and to all control subjects. Results: The mean age of patients was 30.8 years, the mean duration of warts was 4.73 months, the mean number of warts was 9.76 warts and 14.3% of patients experienced side effects to PPD. (58.7%) of patients were completely recovered from warts. Mean serum IL-17 was 81.1 ± 64.2 pg/mL versus 118.9 ± 93.8 pg/mL in genital wart patients versus controls respectively (P < 0.05) and 81.1 ± 64.2 pg/mL versus 107.1 ± 66.8 pg/mL before and after PPD injection respectively (P < 0.05). Conclusion: IL-17 serum level was significantly lower in genital wart patients than normal controls. IL-17 serum level had been increased significantly after PPD intralesional injection than pretreatment levels and significantly related to clinical response to PPD. IL-17 suggested having a role in the clinical efficacy of PPD in the treatment of genital warts.