History and Objectives: Since the prevalence of the urinary infections without clinical symptoms are fairly high among pregnant women, diagnostic values of the nitrate was investigated among individuals referred to the Dr. Shabihkhani hospital of Kashan in 1996.

Materials and Methods: This study was conducted in a descriptive manner in the first phase and as a clinical diagnostic trial in the second phase on 350 samples. Patient records were containing age of pregnancy, number of pregnancies, number of births, education, past urinary infections were recorded by a specialist. Patients were referred to the Central Laboratory and urinary analysis and microbiological test were conducted.

Results: Prevalence of urinary infection was 5.4% (19 individuals) and confidence interval (With the probability of 95%) for the population was 3% (Minimum) and 7.8% (Maximum) respectively. Sensitivity of the nitrate test compared to the culture test was 78.94% and specificity was 99.09% and positive and negative reported values were 83.33 and 98.8 percent respectively. 98% of nitrate tests were in agreement with the culture test.

Conclusion: The present study show that although sensitivity and specificity of the nitrate test was higher compared to previous reports, nitrate urine test for detection symptomatic urinary infection of pregnant women is not logical since undetected cases will pose increased danger to the mother and fetus.