Trichomonas vaginalis, a protozoan causing trichomoniasis, is one of the commonest non-viral sexually transmitted infections (STIs) worldwide. It is a motile trophozoite lives in the lower genitourinary tract of females and the prostate and urethra of men and cause of symptomatic vaginitis in women. T. vaginalis causes serious complications such as increases risk of human immuno-deficiency virus (HIV) transmission in both women and men with the adverse outcomes during pregnancy. Besides, complications for symptomatic women include vaginitis, endometritis, infertility, and cervical cancer, and for men include urethritis, prostatitis, epididymitis, and infertility. The disorder was underdiagnosed the drug of choice is oral metronidaz-ole for both partners but if this fails, clinicians may use other nitroimidazoles. The study enhanced the as to T. vaginalis. Setting: Study was done in a Military Hospital. Design: A quasi-experimental study (pre & posttest) was used. Subjects were 63 nursing staff. Study tools: Composed of socio-demographic characteristics of nurses and knowledge questionnaire sheet and pre & posttest.The results showed statistically significant improvement in the nursing knowledge regarding Trichomonas vaginalis. Recommendations: Developing periodic educational program and evaluation regarding Trichomonas vaginalis on regular basis, would competency to provide high quality nursing care.