Objective: This study aimed synthesis of pyridine and fused pyridine derivatives based on the importance of these heterocycles as anticancer. Method: Novel pyridine and fused pyridine derivatives 3-35 were synthesized through different chemical reactions. Results: Structures of these compounds were confirmed by spectral and elemental analyses. The obtained compounds were evaluated for their in vitro antitumor activity against liver HepG2 and breast MCF-7 cancer cell lines compared to the reference drug (5-fluorouracil). Conclusion: Compounds 4, 12, 13, 19, 21, 28 and 29 were found to be the most active against both cell lines exhibiting IC₅₀ values ranging from 3.05-11.50 μg/mL and 2.87-6.23 μg/mL against HepG-2 and MCF-7 cell lines; respectively