Bacterial vaginosis(BV) is a polymicrobial, noninflammatory syndrome involving the lower genital tract that is characterized by a microecologic imbalance and the replacement of lactobacilli-predominant flora with Gardnerella vaginalis, anaerobes, and Mycoplasma hominis. Microbiological analysis of BV has shown Gardnerella vaginalis to be the most frequent causative organism. This bacterium has been detected in most of BV cases.Moreover,in cases of BV, Gardnerella vaginalis has a symbiotic relationship with anaerobes. The combination of Gardnerella vaginalis, anaerobic bacteria, and Mobiluncus hominis was very frequently seen among women with BV(59.6%), compared with the frequency in women without BV (3.9%). This book focusing on proper, rapid and sensitive methods are required to diagnose bacterial vaginosis because even in the absence of obvious symptoms, many complications may be associated with BV infection. The study aimed to determine the prevalence of Bacterial vaginosis (BV) among women in reproductive age in Saudi Arabia –Riyadh .