A variety of 3-(3-bromo phenyl)-5-phenyl-1-(thiazolo [4,5-b] quinoxaline-2-yl)-2-pyrazoline were obtained by the refluxing of 1-N-thiocarbamoyl 3,5-diphenyl-2-pyrazoline with 2,3-dichloroquinoxaline. The chemical structures of the compounds were elucidated by UV, IR, (1)H NMR, and (13)C NMR spectroscopy. The purity of the compounds was confirmed by their elemental analysis. The antiamoebic activity of these compounds was evaluated by microdilution method against HMI:IMSS strain of Entamoeba histolytica and the IC(50) values were compared with the standard drug metronidazole. Some of the quinoxaline derivatives showed less IC(50) values than metronidazole. To elucidate the toxic effect, MTT assay was performed using kidney epithelial cell line. The results showed that all the compounds are non-toxic.