Two well-described diagnostic methods for bacterial vaginosis are clinical or wet-smear diagnosis (Amsel criteria) and Gram stain diagnosis (Nugent criteria). Our objective was to compare diagnostic Amsel criteria and Gram stain diagnosis of bacterial vaginosis. Between June 1999 and November 2001, all non-pregnant women aged 16 years or older who referred to gynecologic clinic with a complaint of vaginal discharge were examined for detection of bacterial vaginosis by diagnostic methods of Amsel and Gram stain. Clinical diagnosis of bacterial vaginosis (Amsel criteria) was considered positive if at least three of the following four characteristics were seen: a homogenous appearance of the discharge, pH value >4.5, release of a fishy amine odor on addition of potassium hydroxide (Whiff test) and presence of clue cells. Amsel criteria were compared with Gram stain diagnosis. One hundred two patients were diagnosed with bacterial vaginosis. When compared Gram stain diagnosis of bacterial vaginosis as the standard method, Amsel criteria had sensitivity of 78% a specificity of 88% a positive predictive value of 95% and a negative predictive value of 58%. The utility of various single tests for the diagnosis of bacterial vaginosis as compared with the Gram stain showed lower diagnostic validity. Conclusion: Gram stain is a reproducible and reliable test for diagnosis of bacterial vaginosis and Amsel criteria must be confirm by Gram stain.