Abstract
The goal of this contribution is to, based on personal experience from teaching and swimming training, point out substantial deviations which appear during the butterfly technique performance, and at the same time provide the reader with the exercices which can help with beginners teaching or get rid of fixed imperfections of the advanced swimmers. The contrubution is intended for swimming teachers who strive to teach an individual the proper butterfly technique within its rules accurately and, within the bounds of possibility, efficiently.