We performed this prospective study to determine the urinary calcium to creatinine ratio (Ca/Cr) in children with different urinary symptoms. We studied 523 children in our neph-rology clinic with an age range of 3 to 14 years (mean= 8) and male to female ratio of 0.61. All the children had at least one of the urinary tract symptoms (dysuria, frequency, urgency, abdo-minal and/or flank pain, diurnal incontinence or enuresis), microscopic hematuria, urinary tract infection or urolithiasis. Fasting urine was collected for measuring calcium and creatinine and the results were compared to the values for the normal Iranian children. Ca/Cr ratio of more than 0.2 (mg/mg) was considered as hypercalciuria. Of all the patients, 166 (31.3%) were hypercalciuric. Urine Ca/Cr ratio was significantly higher in all the subgroups with one or more of the urinary symptoms (P< 0.001). We conclude that urine Ca/Cr ratio is significantly increased in children with all types of urinary symptoms. We recommend measuring urinary calcium in all children with urinary tract symptoms, especially if unexplained.