Background & Objective: Persistent infection with some types of Human papillomavirus (HPV), which are high-risk genotypes, can lead the patients toward cervical cancer and, finally, death. Recent studies showed HPV co-infection with nonHPV sexually transmitted infections (non-HPV STIs) could increase the persistency rate of HPV infections. This study aimed to estimate the prevalence of STIs and assess the association of HPV/non-HPV STIs co-infection on cervical cell changes based on cytological findings. Materials & Methods: In this cross-sectional study, in addition to the routine cervical screening, including HPV testing and cytological assessment, non-HPV STI testing was performed on 1065 Iranian women. To assess the HPV and non-HPV STIs, commercial kits were used. Results: 964 (90. 5%) women had normal cytology (NILM) results. The overall prevalence of HPV and non-HPV STIs were 39. 1% and 68. 5%, respectively. HPV-53 (6. 5%),-16 (6. 1%) and-31 (5. 5%) were found as the most prevalent genotypes. Ureaplasma Parvum (UP) (42. 7%), Group B Streptococcus (GBS) (23. 7%), Candida Species (CS) (23. 6%), Ureaplasma Urealyticum (UU) (9. 6%), and Mycoplasma Hominis (MH) (7. 1%) were found as the most prevalent non-HPV STIs. The coinfection of HPV with GBS played an important role in developing the cervical lesion (P<0. 05). Conclusion: In the present study, the STIs, including HPV, UP, GBS, CS, UU, and MH, were prevalent among the study participant, and it was found that the HPV/GBS co-infection played a significant role in the development of LSIL or worse cytological grades. To clarify this issue, further studies will be conducted.