C-reactive protein, synthesized by the liver, belongs to the group of proteins in the acute stage of inflammation. It has a very short half life of 6 to 8 hours with rapid evolution kinetics. The CRP level has been measured 959 times by the immuno-turbidimetric method in 500 in-patients of the Gynaecology Department of Claude Bernard Hospital. It was measured every 48 hours. The CRP level increases in the immediate post-operative period, reaches its maximum on D3 and falls back to normal between D5 and D7. The CRP level seems to be the most reliable parameter for the diagnosis of pelvic infections (namely salpingitis). It represents the best criterium to assess the effectiveness of the treatments administered to the infected patients (adnexitis, post-operative complications).