The results of observations and investigations of a new phenomenon -- changes in the macroscopic characteristics of the plastic deformation of metals and alloys at a superconducting transition -- are systematised. In these works it is shown for the first time that the electronic drag of dislocations accompanying low-temperature deformation is effective. The main experimental features of the phenomenon -- the dependences of the characteristics of the change in plasticity at a superconducting transition on the stress, deformation, temperature, deformation rate, and concentration of the alloying element in the superconductor -- and results indicating a correlation between the characteristics of the effect and the superconducting properties are presented. Experiments clarifying the mechanisms of the phenomenon are analysed. A brief exposition of the theoretical investigations of the electronic drag of dislocations in metals in the normal and superconducting states and the influence of a superconducting transition on the plasticity is given. The theoretical results are compared with the experimental results. Examples of the application of the effect as a new method for investigating the physical mechanisms of low-temperature plastic deformation are presented. The applied aspects of the phenomenon are discussed separately.