Interleukin-1β is an important cytokine that plays a role in the acute phase of inflammation seen after infection.The current prospective study involved 30 patients suffering from acute pyelonephritis and receiving antibiotic therapy. Their age ranged from 2 month to 9 years, with a mean value of 4.07 years; they included 13 (43.3%) males and 17 (56.7%) females. Control group included 28 apparently healthy children.Out of 30 patients, all of them were culture positive, 19 (63.3%) patients had a high grade fever, 7 (23.3%) patients had positive CRP test, and 6 (20%) patients had casts in their urine. Cytokine (IL-1β) urinary level was evaluated among acute pyelonephritic pediatric patients.Urinary level of IL-1β was significantly elevated in patients regardless of the causative organism as compared to normal controls.