3-Methyl-1-phenyl-6-pyrrol-1-yl-1H-pyrazolo[3,4-b]pyrazine-5-carboxylic acid hydrazide (5) could be obtained in a four-step reaction starting from 6-amino-3-methyl-1-phenyl-1H-pyrazolo[3,4-b]pyrazine-4-carbonitrile 1. The latter compound was used as a key intermediate for the synthesis of several new pyrazolo[3,4-b]pyrazine derivatives. The structure of all the new compounds was established on the basis of their analytical and spectral analyses. The antibacterial and antifungal activities of nineteen of the synthesized compounds were evaluated against some various strains of bacteria and fungi, using streptomycin and clotrimazole as reference drugs respectively. Certain derivatives showed promising results.