BACKGROUND: Sexually transmitted infections (STIs) are a group of infections that are predominantly transmitted through unprotected sexually contact with an infected person (MOHSW, 2008). The infections presenting with common signs and symptoms which are vaginal discharge, urethral discharge, burning sensation during urination for men, genital ulcers and abdominal pain although sometimes doesn’t shows any signs and symptoms. More than a million people get infected with STIs everyday, for the global burden of STIs an estimated 499 million new cases of curable STIs occurred in 2008 shows there is no improvement over the 2005 estimate of 448 million cases (WHO, 2013). A study done on pregnant women in Moshi Urban district from June 2002 to March 2004 showed that rates of STIs and RTIs are still high among pregnant women in Moshi. Study results for prevalence were 0.9% for active syphilis, 33.6% herpes simplex virus type 2, and those who were tested gave the results of 0.5% Neisseria gonorrhea, 5.0% Trichomonas vaginalis and 20.9% Bacterial vaginosis (Msuya et al, 2009). OBJECTIVE: This study aims at determining the prevalence of curable sexually transmitted infections among males and females aged 15-49 years attended STI clinic at Majengo health center in Moshi and compare the prevalence of such infections between them. METHODOLOGY: The proposed study was hospital based, cross sectional descriptive study. Data was collected through the reviewing of the sexually transmitted infections registers from Jan 2014 to Dec 2015 at Majengo Health Centre. The study included all Males and Females aged 15-49 years who were diagnosed with curable sexually transmitted infections attended at Majengo Health Centre from January 2014 to December 2015. The study also showed the difference in occurrence of such infections between males and females attended to at that period. RESULTS: Based on the syndromic diagnosis, among 331 Male and Female patients attended STI clinic at Majengo health center from Jan 2014 to Dec 2015 the study found 14.2% had urethral discharge syndrome which indicated infections of Neisseria gonorrhea, Chlamydia trachomatis and Trichomonas varginalis for males, 68.8% had abnormal vaginal discharge syndrome which indicated infections of Gonorrhea, Trichomoniasis, chlamydia and Candidiasis ix for Females, 12.5% had Genital ulcerations which indicated infection of syphilis, chancroid and herpes simplex-2 for both sex, 3.9% had pelvic inflammatory disease for Females and 0.6% had painful scrotal swelling for Males. Also the study found that the prevalence of STIs is higher 82.8% for Females attended STI clinic at Majengo health center compared to Males 17.2%. CONCLUSION: Conclusively, the results of the current study showed that, there was a prevalence of curable sexually transmitted infections among males and female patients attended STI clinic at Majengo health center, also females showed to have higher prevalence compared to males. Also the study found the common types of STIs to be Gonorrhoea, Trichomoniasis, Chlamydia, Syphilis and candidiasis.