In this work, a novel series of 9‐amino‐7‐aryl‐11‐imino‐2,4,8,10‐tetraazaspiro[5.5]undeca‐7,9‐diene‐1,3,5‐triones 3a‐l was synthesized via the treatment of cyanoguanidine 1 with respective arylidene barbituric acids 2a‐l in dry pyridine. The products were evaluated for in vitro antibacterial activity against Bacillus cereus (+G), Staphylococcus aureus (+G), Pseudomonas aeruginosa (−G) and Escherichia coli (−G). The results showed that some of the tested products are promising antibacterial drugs.