A stability indicating gradient reversed-phase liquid chromatographic (RP-LC) related substance method for SAdenosyl- L-methionine (SAMe) in active pharmaceutical ingredient was developed and validated. SAMe was subjected to stress conditions and observed sensitive to alkali hydrolysis, oxidation and thermal degradation. Successful separation of SAMe from its process and degradation related impurities was achieved on a YMC-Pack Pro-C18, 150 mm × 4.6 mm, 3μm column using a gradient mixture of solvent A (mixture of 0.015 M citric acid monohydrate, 0.01 M sodium dihydrogen orthophosphate dihydrate, 0.014 M sodium lauryl sulphate and acetonitrile in the ratio of 75:25 v/v) and solvent B (mixture of 0.004 M citric acid monohydrate, 0.003 M sodium dihydrogen orthophosphate dihydrate, 0.014 M sodium lauryl sulphate and acetonitrile in the ratio of 20:80 v/v). The flow rate was 1.5 mL/min and the detection wavelength was 254 nm. The mass balance was found to be in the range of 99.1 - 99.9% in all the stressed conditions.