To counteract the resistance produced by microbes there is a need to invent new drugs, which are more safe and effective. In many cases heterocyclic fusion with pyrimidine ring resulted in compounds with wide spectrum of biological activities. Thienopyrimidines, the structural analogues of biogenic purine class, undoubtedly, has high significance in the field of pharmaceutical and biotechnological sciences, with wide spectrum of biological activities. In continuation of our research program to find out bioactive thienopyrimidines, the present work is an effort towards the synthesis, characterisation and evaluation of 3-substituted-thieno[2,3-d]pyrimidine-4-ones for their antibacterial, anti-inflammatory and antioxidant activity. Three compounds (6a, 6d, 7f) were found to possess moderate anti-bacterial activity against both micro-organisms when compared to Procaine penicillin (gram +ve) and Streptomycin (gram –ve). Compounds 6a, 6c and 7a were found to possess good anti-inflammatory activity when compared to Diclofenec sodium. The study regarding anti oxidant activity shown that thienopyrimidines are not anti-oxidants. Further lead optimization should be carried out for the better expected anti-inflammatory or antibacterial activity.