The present work focused on exploring the reactivity of β-nitrostyrene towards Mannich reaction with different approaches. The synthesized nitro-Mannich bases were tested as antimicrobial agents that showed high activity against both gram positive and gram negative bacteria. N-[1-(2-Nitro-1-phenyl)ethyl]-4,4`-trimethylenedipiperidine (5): A mixture of β-nitrostyrene (0.15 g, 0.001 mol) and 4,4`-trimethylenedipiperidine (1 g, 0.005 mol) in ethanol (20 ml) was warmed on a steam bath for five minutes with stirring, then left to cool at room temperature for about one hour then diluted with cold water. The precipitate that formed was filtered off, dried and washed well with hot (ethanol-ethylacetate) to give compound 5 as a pale brown powder m.p. 140-141ºC; yield 1.