Bacterial vaginosis is the most common cause of vaginitis in women of reproductive age. In an attempt to clarify diagnosis of this condition, various parameters of signs and symptoms and groups of parameters were compared with classical diagnostic criteria in 310 patients. There was no significant difference in positive diagnosis rates between the Amsel et al. criteria and those of Thomason et al. (p = 0.25). The single most reliable indicator of bacterial vaginosis was the presence of clue cells on wet mount examination of vaginal secretions (sensitivity 98.2%, specificity 94.3%, positive predictive value 89.9%, negative predictive value 99.0%). The best two combinations of parameters for rapid accurate clinical diagnosis were clue cells and odor on alkalinization (sensitivity 99.5%) positive predictive value 98.8%, negative predictive value 92.1%). Gram stain criteria (bacterial morphologic types) were less accurate predictors of the disease (sensitivity 97.0%, specificity 66.2%, positive value 57.2%, negative predictive value 97.9%). Even when the bacterial morphologic type criteria were combined with presence of clue cells, predictive accuracy did not exceed that of clue cells on wet mount examination alone (sensitivity 93.9%, specificity 84.7%, positive predictive value 74.2%, negative predictive value 96.8%). Homogeneous discharge was found to be of little diagnostic value.