5-Methyl-3,8-di-(2-amino-4-bromophenyl)-4,9-dioxa-1,2,6,7-tetraaza-5λ 5 -phosphaspiro [4.4]nona-2,7-diene was obtained by condensation of 2-amino-5-bromobenzohydrazide and methylphosphonyl dichloride in the presence of triethylamine. An initial biological screening was performed for the resulting product. The synthesized compound showed relatively strong cytotoxic activity, which was, however, similar for cancer and non-cancer cell lines.