A simple, sensitive, reliable, and rapid high-performance liquid chromatographic method for the simultaneous determination of phloroglucinol and trimethyl phloroglucinol has been developed. Acetonitrile-water (1:1 v/v) was used as mobile phase, with flow rate 2 ml/minutes. pH was adjusted to 3 with phosphoric acid. U.V detection was performed at 242 nm. The results obtained showed a good agreement with the declared content. Recovery values for phloroglucinol were from 99.91% to 100.62% and recovery values for trimethylphloroglucinol were from 98.44% to 100.04%. The proposed method is rapid, accurate, and selective, it may be used for the quantitative analysis of phloroglucinol and trimethylphloroglucinol. The method was found to be specific, accurate, precise and reliable for the determination of phloroglucinol and trimethylphloroglucinol in the form of raw materials, in bulk drugs and formulation. It was possible to determine both phloroglucinol and trimethylphloroglucinol in the concentration range of 5 nano gram to 30 nano grams. The detection limit of both phloroglucinol and trimethylphloroglucinol were 0.4 nano gram.