A series of pyrazolopyridine and pyridopyrimidine derivatives 2-6 were newly synthesized using 3,5-bisarylmethylene-1-methylpiperidone as the starting material. The anticancer activities of the synthesized compounds were evaluated using 59 different human tumor cell lines, representing cancers of CNS, ovary, renal, breast, colon, lung, leukemia, and melanoma, prostate as well as kidney. Some of the tested compounds, especially those with a fluorine substituent at the para-position in the phenyl ring and those with a pyridopyrimidine-2-thione with a free -NH or -SH, exhibited greater in vitro anti-tumor activities at low concentrations (log 10 [GI₅₀] = -4.6) against the human tumor cell lines. Additionally, some of the compounds had moderate inhibitory effects on the growth of the cancer cell lines. The detailed synthesis, spectroscopic data and antitumor properties of the synthesized compounds are reported.