PCR technique was used for the detection of S. typhi and compared to conventional culture results to identify S. typhi and determine the relative sensitivity and specificity of these methods. From 254 blood specimens were collected from typhoid fever patients ,207(84.48%) isolated bacteria were obtained and isolated from three groups of patients, group Ι was positive of PCR and blood culture, group ΙΙ was positive of blood culture but it was negative of PCR, and group ΙΙΙ was positive for intracellular bacteria isolatingو methods when it’s negative for blood culture and then compared result with typical Salmonella enterica serovar typhi strain taken from central health laboratory However, 203 (94.4%) isolates were observed positive to nested PCR and 168 (78.1%) was observed positivity by bacteriological and serological methods to identify of isolated bacteria from typhoid patients’ blood. When the more specific tests were evaluated in the diagnosis and identify of isolated bacteria that were positive by any of the two tests employed (n = 207), the nested PCR resulted in a relative sensitivity of 98.06% and specificity of 100% when compared with bacteriological and serological methods.