Some new N-acyclic pyridazine nucleosides 2-5 and S-acyclic pyridazine nucleosides 8-10 were prepared from compounds 4,6-diphenyl-2H-pyridazin-3-one (1) and 4,6-diphenyl-2H-pyridazin-3-thione (7), respectively. Also, the hydrazino derivative 11 was prepared and used as a key compound for the preparation of some [1,2,4]triazolo[4,3-b]pyridazines 12-15. Moreover, the cytotoxicity and in vitro anticancer evaluation of some prepared compounds have also been assessed against different cancer cells including Lung (A594), Colon (HCT116), Breast (MCF-7), Liver (HepG2) and Prostate (PC3) as well as normal Melanocyte (HFB4). The results revealed that compounds 3 and 10 have moderate anticancer activities; while compounds 1, 2, 8, and 11 possess promising anticancer activities against breast MCF-7 and liver HepG2 cancer cell lines compared to the activity of the commonly used anticancer drug, doxorubicin. Otherwise, the results revealed that the previous compounds have no toxic effect against the normal HFB4 cells.