In an effort to establish new pyrroles and pyrrolo[2,3-d] pyrimidines with improved antimicrobial activity we report here the synthesis and in vitro microbiological evaluation of a series of pyrrole derivatives. A series of new 2-aminopyrrole-3-carbonitriles (1a-d) were synthesized from the reaction of benzoin, primary aromatic amines and malononitrile, from which a number of pyrrole derivatives (2a-d to 5a-d) and pyrrolo[2,3-d]pyrimidines (6a-d to 10a, d) were synthesized. The in vitro antimicrobial testing of the synthesized compounds was carried out against Gram-positive, Gram-negative bacteria and fungi. Some of the prepared compounds, [2-amino-1-(2-methylphenyl)-4,5-diphenyl-1H-pyrrole-3-carbonitriles (1b), 2-amino-3-carbamoyl-1-(3-methylphenyl)-4,5-diphenyl-1H-pyrroles (2b), N-(3-cyano-1-(2-methylphenyl)-4,5-diphenyl-1H-pyrrol-2-yl)-acetamides (3b), N-(3-cyano-1-(3-methylphenyl)-4,5-diphenyl-1H-pyrrol-2-yl)-acetamides (3c), 2-amino-1-(4-methoxyphenyl)-4,5-diphenyl-3-tetrazolo-1H-pyrroles (5d), 7-(4-methoxyphenyl)-5,6-diphenyl-7H-pyrrolo [2,3-d]pyrimidin-4(3H)-ones (7d), 7-(3-methylphenyl)-5,6-diphenyl-7H-pyrrolo[2,3-d]pyrimidin-4(3H)-thione (9b) and N-(7-(2-methylphenyl)-5,6-diphenyl-7H-pyrrolo[2,3-d] pyrimidine)-N-aryl amines (10a)] showed potent antimicrobial activity.