Two sensitive and fast spectrophotometric methods using batch and flow-injection procedures for the determination of cimetidine (CMT) are proposed. The methods are based on the formation of a green complex between this drug and Cu(II) in acetic/acetate medium of pH 5.9. The calibration graphs resulting from measuring the absorbance at 330 nm are linear over the ranges 2.5 x 10(-6)-1.0 x 10(-3) and 5 x 10(-6)-2.0 x 10(-3) M with detection limits of 9.5 x 10(-7) and 2.1 x 10(-6) for batch and flow-injection methods, respectively. The methods are applied to the routine analysis of CMT in pharmaceuticals and human urine.