Objective: The primary aim of the study was to find out a suitable effective dose of metanil yellow that can cause alterations of lipid peroxidation and catalase activity in the heart in vitro and to determine the effectiveness of graded doses of Coriandrum sativum as an antioxidant in preventing lipid peroxidative damage to cardiac tissue and back up catalase activity. Methods:Metanil yellow at different doses (10, 25, 35, 50 µl in phosphate buffer) were applied on isolated hircine heart homogenate (10%) in in vitro followed by estimation of lipid peroxidation and catalase activity after completion of the incubation period. Another set of the experiment included incubation of the heart homogenates with graded dilutions of ethanolic leaf extracts of Coriandrum sativum (CsEth) at concentrations of 10, 20, 30, 40 µl in phosphate buffer medium followed by quantification of the same biochemical parameters as above. This was followed by coadministration of the selected effective dose of metanil yellow (35 µl) and ethanolic leaf extract of Coriandrum sativum (30 µl) on heart homogenate to track the variation in lipid peroxidation and catalase activity in heart homogenate in vitro.