This work aimed to evaluate the role of cathelicidin LL37 as a diagnostic marker of urinary tract infection . This study was carried out on 50 patients suffering from symptoms and signs of urinary tract infection(proven UTI group) attending department of Urology at Benha University ,20 patients with clinically diagnosed UTI & culture negative urine(suspected group) and 20 control healthy volunteers matched age and sex with the cases and with no current or previous history of UTI. LL37 level was detected in urine samples of the three group of the study by LL37 Enzyme linked immunosorbent assay(ELISA). In the study high significance of the culture among the three groups of the study(p