Aim of this study is to confirm and investigate the diuretic effect of crocine which is the pharmacologically active component of Crocus sativus L. (saffron) and to study the possible mechanism of action in relation to urinary nitrite. Twenty four rats were divided into 3 groups; control, hydrochlorothiazide and crocine treated groups. Assay of the diuretic activity of crocine was performed by determination of urine volume, urine sodium and chloride. Creatinine clearance or urinary nitrites were measured. Hydrochlorothiazide is chosen as a standard diuretic because it has moderate potency and an  intermediate duration of action.  oral administration of Both Hydrochlorothiazide and Crocin produced a significant increase of the 5 hours urine volume, urine sodium and chloride. Oral administration of crocin produced a significant increase of creatinine clearance and urinary nitrites. Crocine has a diuretic effect in rats. It induces its diuretic effect partially through simulation of Nitric oxide.