ASERIES of pyrimidine and fused triazolopyrimidine derivatives were newly synthesized using aminopyrazole carbonitrile 1 as a had starting material and compounds 14 and 16 are intermediates. Initially, the acute toxicity of the compounds was assayed via the determination of their LD50, and all compounds were interestingly less toxic and had lower ulcerogenic activities than Diclophenac® as a reference drug. Regarding the protection against Carrageenan induced edema; the pharmacological screening showed that compounds 17, 11, 13 and 5 have good anti-inflammatory activities comparable to the reference drug. On the other hand, in searching for COX-2 inhibitor, the inhibition of plasma prostaglandine (PGE2) for the compounds was determined and the same four compounds were found the more potent agents. The detailed synthesis, spectroscopic data, pharmacological screening and acute toxicity LD50 for the synthesized compounds were reported.