OBJECTIVE: The study aim was to evaluate inflammation markers values (C-reactive protein (CRP), Erythrocite sedimentation (ES), White blood cells count (WBC)) in surgically treated pediatric patients with diagnosed developmental displasia of the hip or Perthes disease before and after operation. METHODS: We have evaluated 43 children (20 patients were with diagnosed unilateral developmental displasia of the hip while 23 had Perthes disease). Blood samples were drown at the admission and 5 days after admission, and further inflammatory parameters were analyzed: ES (mm/hour), CRP (mg/L) and WBC (x1000/mm3) count. RESULTS: Elevated erythrocite sedimentation (ESR) was significantly frequent than elevated CRP (p<0.01) and elevated WBC as well (p<0.01). Values of ESR and WBC do not correlate closely with age (FESR= 1.805; FWBC= 0.130; p>0.05) while CRP values correlate significantly with the age of the patients (FCRP= 4.948; p<0.05). The most frequently isolated marker was ESR (34.88%). The most frequent elevated two markers were ESR and CRP (44.19%). CONCLUSION: Surgical procedure could alter the values of inflammatory markers leading to the increasement even though there is no other clinical signs of infection. For estimation of the possible presence of the infection, clinical signs and patients intensive clinical follow-up after the surgery, should be done along with the evaluation of inflammatory markers.