The priming effects of granulocyte colony stimulating factor (G-CSF) on neutrophil function and anti-pseudomonal activity were examined under various osmotic conditions created with urea and NaCL (280mOsm., 400mOsm., 800mOsm.) in vitro. Consequently, the prophylactic effect of G-CSF on post-operative urinary tract infection after transurethral resection of the prostate were examined experimentally. As a result, neutropil chemiluminescence was significantly enhanced by G-CSF under physiological osmotic conditions. However, enhancement was not observed under hyperosmotic conditions as in the urine. Similarly, the anti-pseudomonal activity of human neutrophils was not enhanced by G-CSF under hyperosmotic condition. However, whole blood chemiluminescence in patients after transurethral resection of the prostate was significantly enhanced by the administration of G-CSF. Moreover, postoperative urinary tract infection, considered an infection of the submucosal layer, was not obsereved, suggesting that the neutrophil priming effect occurred in the submucosal layer not in the urinary tract.