The present study describes a simple, specific, sensitive, rapid and economical U.V. spectroscopy method for estimation clarithromycin concentration for gastric pH sensitive formulation. The absorption maxima or λmax of the drug was found to be 353 nm. A linear response was observed in the range of 2-40 μg/ml in simulated buffer solution (pH 1.2) and phthalate buffer solution (pH 3.4) with a regression coefficient (r2) of 0.9812 and 0.9808 respectively. The characteristics analyzed in simulated gastric fluid like slope, intercept, correlation coefficient(r), standard deviation, LOD, and LOQ, were found to be 0.63, 0.053, 0.9822, 0.261, 1.242 μg/ml and 4.14 μg/ml respectively whereas in phthalate buffer (pH 3.4) the value of slope, intercept, correlation coefficient, standard deviation, LOD, and LOQ were found to be 0.62, 0.045, 0.9295, 0.198, 0.958 μg/ml and 3.19 μg/ml respectively. The low values of LOQ and LOD of the proposed method can be used for the determination of amoxicillin trihydrate in quality control of acidic pH sensitive formulation without interference of the excipients.