In this paper, the genre of the theatrical adaptation made by authors themselves in Russian fairytale drama of 1930–1950s is studied. The process of adaptation for the stage of non-dramatic works by their authors was rather widespread and productive during that period. As a result, such classical children’s fairytale dramas as «Tri tolstyaka» («Three fat men») by Yu.K. Olesha, «Zolotoy kluchik» («A small gold key») by A.N. Tolstoy, «V gostyakh u Kashcheya» («On a visit at Kashchey’s») by V.A. Kaverin had been created. In the article, the transformations made by the authors in the course of transposition of original works into drama form are analyzed. The main changes consist in sharpening and deepening of conflicts, strengthening of logical motivations, special construction of the composition, enrichment of characteristics of heroes and introduction of new characters. Nevertheless, such fundamental features of texts as an author’s position, a perspective, main conflicts, a system of heroes and a plot usually are preserved.