5-Amino-3-methyl-1-phenyl-1H-pyrazole-4-carbonitrile (5) was reacted with chloroacetyl chloride under fusion condition to afford two compounds, which identified as 6-chloromethylpyrazolo[3,4-d]pyrimdine (3) and 4-amino-5-chloropyrazolo[3,4-b]pyridine (7) ln different ratios. Treatment of compound (3) with aromatic amines, gave the arylaminomethyl derivatives (8a-c). Compound (3) was reacted with sodium azide, phosphorous oxychloride, sulphanilamide to give new derivatives (9, 10, and 14). The 4-chloro derivative (11) underwent nucleophilic substitution using some reagent such as P2S5, sodium azide and hydrazine hydrate to furnish novel pyrazolo[3,4-d]pyrimidines (12, 13, 15, 16, 17). All synthesized compounds were characterized using elemental analysis and spectral techniques. The antiinflammatory activity of all the newly synthesized compounds was evaluated using the carrageenan induced paw oedema test in rats using indomethacin as the reference drug.