The study involved 183 patients, whom open splenectomy was performed on the traumatic splenic injury. According to haemograms date, were calculated 19 haematological indices and among them detected indices which the most precisely describe reaction of blood system in post-operative period. Also were revealed indices which correlate in post-operative period with values of delay between admission to a hospital and starting the operation. Monitoring of selected haematological indices will help to accurately assess of blood system reaction in patients with traumatic splenic injury in post-operative period.