Summary: Acute urinary retention (AUR) in children is rare and requires urgent intervention. It is defined as the inability to void for more than 12 hours with the volume of urine in the bladder greater than the age-appropriate or the presence of an enlarged bladder on palpation. The etiology is heterogeneous, in young children urinary tract infection and genitourinary inflammation predominates. Among the obstructive factors, the most common are urolithiasis, foreign bodies and constipation, less common but the most dangerous are malignant tumors that require diagnosis and oncological treatment as soon as possible. Other etiological factors include anomalies of the urinary tract, neurogenic and non-neurogenic bladder disorders, drugs and substances with anticholinergic effects, psychogical factors. In many cases, a thorough medical interview and a careful physical examination make it possible to determine the cause of AUR at this stage. In further action, the key issue is to empty the bladder through catheterization or spontaneous micturition and send urine samples for general and bacteriological tests. The ultrasound examination result is very important diagnostically and determines the type of extended diagnostics, treatment and hospitalization. Therapy depends on the cause of AUR and the child's age.