Distinguishing between re-infection and relapse of trichomonas infections is often a difficult task in the clinical setting. The chronicity of trichomonas infections and the ongoing sexual activity are two confounding factors. We present a patient with recurrent resistant vaginal trichomoniasis shortly following a sexual contact with an untreated partner after a complete response to treatment with tinidazole for nine months. We hypothesise that re-infection occurred from the asymptomatic partner who was an untreated chronic carrier of resistant trichomonas in the urogenital tract.