Three derivatives spectrophotometric methods have been described for the assay of amoxycillin in urine. The methods were based on the amplitude measurements of second derivative (D2), first derivative difference (delta D1) or second derivative difference (delta D2) curves. These values were linearly correlated to the amoxycillin concentration in the range of 0.2-1.0 mg% with negligible intercepts. The absolute recovery from urine specimens was found to be 98%. The within-day and between-day precision were satisfactory.