Purines and pyrimidine derivatives are the important class of compounds in medicinal chemistry. Pyrimidine – a totally unsaturated six membered ring containing nitrogen at 1,3-position. They represent the diazine family with urazil and thymine being the constituents of ribonucleic acid (RNA) and deoxyribonucleic acid (DNA) and with cytosine. The work highlights one pot synthesis of some 1,3-dihydro pyrimidine derivatives from different substituted aldehydes. All the synthesized derivatives were screened for antibacterial activity using  gram positive (Bacillus subtilis, Staphylococcus aureus) and gram negative (Pseudomona aeruginosa, Escherichia coli) organisms at concentrations of 400μg/disc and 200μg/disc. The compound 5b (p-dimethyl aminophenyl derivative) was found to be sensitive in all strains. The structure of compound 5b was confirmed by IR spectral studies.