A compound endowed with coanthracyclinic activity should potentiate the antitumor activity of anthracyclines report the synthesis and configuration of a series of substituted while counteracting their cardiodepressant effect. We now the 3-(5-imidazo[2,1-b]thiazolylmethylene)-2-indolinones which were tested for both cardiotonic and cytotoxic activity. Several compounds were potent cytotoxic agents and two of them (in particular 3-[6-(2,5-dimethoxyphenyl)-5-imidazo[2,1-b]thiazolylmethylene]-2-indolinone), which showed even cardiotonic activity, are potential coanthracyclinic agents.