Various 6-aralkyl-9-substituted-6H-indolo[2,3-b]quinoxalines were synthesized by reaction of 1,5-disubstituted 2,3-dioxo-2,3-dihydroindole and orthophenylene diamine. Appreciable anticancer activity of compounds 5b, 5d, 5g and 5l at various cell lines among 59 human tumor cell panels was observed. All the synthesized compounds were evaluated for cytostatic activity against human Molt 4/C8 and CEM T-lymphocytes as well as for murine L1210 leukemia cells. Compound 5h exhibited an I C50 of 23 micromol L(-1) against Molt 4/C8 and 38 micromol L(-1) against CEM compared to melphalan 3.2 micromol L(-1) and 2.5 micromol L(-1), respectively. The IC(50) for compound 7i against L1210 was 7.2 micromol L(-1) compared to melphalan 2.1 micromol L(-1).