Objectives: To develop simple, rapid, accurate methods for determination of rubraxanthone in the stem bark extract of Garcinia cowa using High Performance Thin Layer Chromatography (HPTLC) and High Performance Liquid Chromatography (HPLC). Methods: The HPTLC method was performed on aluminum plate precoated with silica gel 60 F254 using Chloroform: Ethyl acetate: Methanol: Formic acid (88:2:2:8) as a developing system. Quantification was achieved using densitometric measurements at 243 nm. The HPLC method involved a 5 μm C18 column and an isocratic solvent using 0.4% formic acid: methanol (12:88) with a flow rate 1 mL minute-1. Quantitation was also achieved with ultraviolet detection at 243 nm based on peak area. All necessary validation tests for both methods were done for their comparison. The results obtained by these two different quantification methods were compared by Tukey’s-test. Results: Both assays provided good linearity, accuracy, precision, specificity and limits of detection and quantitation for determination of rubraxanthone in The Stem Bark extract of G. cowa. Conclusion: Both methods revealed reasonable validation parameters concerning linearity, accuracy, precision, specificity and limits of detection and quantitation. A statistical comparison of the quantitative analysis of rubraxanthone in extract did not show any statistically significant difference between two analysis methods. As both methods were found to be equal, they therefore can be used for the analysis of rubraxanthone in the Stem Bark extract of G. cowa.