Immunoactive ionic liquids (2-hydroxyethyl)ammonium 1-R-indol-3-ylsulfanyl-acetates HN+R1R2(CH2CH2OH) ∙ -O(O)CCH2S-Ind-R3-1 (1-5), were synthesized by the reaction of (2-hydroxyethyl)amines with indol-3-ylsulfanylacetic- or 1-benzylindol-3-ylsulfanylacetic acid. 1: R1 = R2 = CH2CH2OH, R3 = H; 2: R1 = СН3,R2=CH2CH2OH, R3 = H; 3: R1 = R2 = CH3, R3 = H; 4: R1 = R2 = CH2CH2OH, R3 = СH2С6Н5; 5: R1 = СН3; R2 = CH2CH2OH; R3 = СH2С6Н5. The structure of each compound was elucidated by IR, NMR 1H, 13С, and 15N techniques and their composition was confirmed by elemental analysis. The crystal structure of tris-(2-hydroxyethyl) ammonium indol-3-ylsulfanylacetate was investigated by X-ray diffraction analysis. Immunoactive properties of the title compounds were screened.