In this monograph, the authors tried to reflect the history of the development of medium tanks of the pre-war period. In the early 30s, domestic designers completed a number of projects of medium tanks, manufactured and tested prototypes, but only T-24, T-28, T-29, and then the legendary T-34 were adopted. Unlike the T-28 and T-34, the T-24 tank, released by a batch of 25 cars, did not leave a bright trace in the history of the domestic tank industry, the T-29 medium wheel-tracked tank was withdrawn from service shortly after adoption and was not serially produced. Nevertheless, the design of this machine and other prototypes of medium tanks of the pre-war period deserves some attention. Since the most detailed history of the creation and development of medium tanks T-28 and T-34 is covered in the books prepared for publication Middle tank T-28? and Unknown thirty-four?, In this monograph, to exclude a violation of the chronological order, only a brief history of the creation of the T-28 tank and pre-war samples of the T-34 tank is given.