A stability indicating HPLC method was developed and validated for quantitative determination of agomelatine in plasma and tablet formulation in the presence of degradation products generated from forced degradation studies. An HPLC method was developed to separate the drug from the degradation products using Waters spherisorb Cyano C₁₈ column (250 x4.6mm, 5μm) and a mobile phase constituted of trifluoroacetic acid buffer and methanol (50:50 % v/v). The wave length of the detection is 230 nm at a flow rate 1mL/min. The validation data showed that the assay is accurate, precise, sensitive, specific and reproducible for the determination of agomelatine in plasma as well as in tablet formulation in the presence of its degradants. The method is linear from 12.5-37.5 μgmL^-1 and accuracy of the method was found to be 100.5 -100.9 % for tablets and 97.84 – 101.24% for plasma. The proposed method was found to be suitable for quantitative determination and the stability study of the drug in plasma and tablet formulation.