In view of developing novel and effective antimicrobial agents, novel series of pyrazolines (4a-g and 5a-g) bearing 2,3,4-trichlorophenyl moiety were synthesized by treating 1-(2,3,4-trichlorophenyl)-3-(4-aryl)-2-propene-1-ones (3) with hydrazine hydrate and formic acid/ acetic acid (Schemes 1 and 2).  The newly synthesized compounds were characterized by elemental analysis and spectroscopic studies and screened for their in vitro antibacterial and antifungal activities. The screening studies revealed that the novel pyrazoline derivatives (4a-g and 5a-g) exhibited moderate to good activity.