The retention behaviour of some alkaloids, as test samples, on reversed-phase pre-coated thin layer chromatography in the presence of different ion-pair reagents was investigated. Trifluoroacetic acid (TFA), pentafluoropropionic acid (PFPA), and heptaflluorobutyric acid (HFBA) were used as counter ions. The dependence of RFvalues on the eluent composition, the chain length of the ion-pair reagent and the ratio of two ion-pair reagents in the eluent is described. The retention values of the tested alkaloids after impregnation of the plate with the counter ion, were investigated.