The composition of carboxylic acids of the rhizomes of Iris carthaliniae and Iris medwedewii by the gas chromatography - mass spectrometry method has been studied for the first time. The total content of carboxylic acids for I. carthaliniae was 1.34%, including (%) - 0.65 fatty; 0.36 mono-, di- and tri-carboxylic; 0.33 phenol carboxylic acids. The yield of carboxylic acids for I. medwedewii was 1.58%, including (%) - 0.73 fatty; 0.38 mono-, di- and tri-carboxylic; 0.47 phenol carboxylic acids. The dominant fatty acids in the rhizomes of I. carthaliniae were myristic acid (25%), palmitic acid (14.41%), stearic acid (10.51%) and linoleic acid (6.05%). Besides, levulinic acid (15.84%) and oxalic acid (4.42%) prevailed among organic acids, while ferulic acid (2.43%), citric acid (1.88%) and malic acid (3.62%) prevailed among the hydroxy acids. The fatty acids palmitic acid (6.51%), linoleic acid (8.38%), oleic acid (3.87%) and capric acid (3.21%) were found in the rhizomes of I. medwedewii, and also, levulinic (29.39%), malonic (1.45%), succinic (1.72%) acids prevailed among the organic acids and citric (25.37%), malic (3.30%) and ferulic (2.42%) acids in the rhizomes of I. medwedewii prevailed among the hydroxy acids.Key words: Iris carthaliniae Iris medwedewii rhizomes carboxylic acids GC-MS analysis.