A prospective study of 50 samples of patients suffering from different bone and joint infections at Al-Hussien Teaching Hospital at period from January to August 2020. The mean age is 47.98 years, 60% males and 40% females, 24% of the cases were diabetes mellitus, 24% of the cases were immunosuppression, and 16% of the cases were suffering from obesity. These samples examine by conventional culture and by molecular method (PCR and DNA sequences) to evaluate the specificity and sensitivity for each method in the diagnosis of bone and joint infection to know the best and shorter method in the diagnosis. The results revealed the specificity and sensitivity of molecular method are (93.75%) and (88.24%) respectively, while by cultural method they are (81.25%) and (94.12%) respectively. All the patients were sent for measuring C–Reactive protein, peripheral blood leucocytes and HbA1c to evaluate diabetes mellitus. Also all the patients sent for plain radiography and ultrasound. In this study we evaluate the risk factor for etiology of bone and joint infection such as immunosuppression and obesity. Also evaluate the type of implants, localization of infection, purulence of infection and presence of sinus tract. We proved in this study that the molecular method is more specific but less sensitive than the conventional culture in the diagnosis of bone and joint infections.