The reaction of 1H-pyrazole-3-carboxylic acid chloride (1) with various hydrazine derivatives 2a-c yielded the corresponding N,N-disubstituted 4-benzoyl-1,5-diphenyl-1H-pyrazole-3-carbohydrazides 3a-c. These products underwent Friedel-Crafts acylations with arenes to afford compounds 4a-c. Treatment of 1 with aromatic diamines produced 1H-pyrazole-3-carboxamides 5a-c, which were allowed to react with phenylhydrazine to give hydrazone derivatives 6a-c. The structures of all new compounds were established by IR, H-1 and C-13 NMR data and elemental analyses. The new compounds were evaluated for antimicrobial activities against Gram (-), Gram (+) bacteria and two yeasts using the disc diffusion method. N,N-Dimethylhydrazide derivative 3a is the most active compound of the series.