In this paper, we describe our results of the synthesis and biological testing of analogues of the natural alkaloids olivacine and ellipticine. We have synthesized fourteen new 1-substituted pyrido[4,3-b]carbazole derivatives. All of them were tested in vitro for their anticancer activity on three human tumor cell lines: CCRF/CEM (T lymphoblast leukemia), A549 (lung adenocarcinoma), and MCF7 (breast cancer). Cytotoxicity to non-cancer cells was estimated in cultures of the mice fibroblast cell line 3T3 BALB. The anticancer activity of 9-methoxy-5,6-dimethyl-1-[(1,1-bis-hydroxymethyI-propylamino)-methyl]-6H-pyrido[4,3-b]carbazole (compound 9) was the strongest amongst compounds tested on the three cancer cell lines; it was about 5 times higher than ellipticine and about 10% higher than doxorubicin.