This work shows the first experience of cyclic steam stimulations of vertical wells with radial horizontal bores in the deep heavy oil carbonates of the Usinsk Permian - Carboniferous reservoir. In the end of 2006, more than 30 radial horizontal bores of approximately 100 m length each were drilled in 8 vertical wells, 5 of which were then stimulated by steam injection. Radial drilling in low productivity carbonates without the following cyclic steam stimulations were ineffective because it did not resulted in significant increase in the well productivity. Integrating radial drilling and cyclic steam stimulations proved highly effective by reducing oil viscosity. The average growth of oil rate was about 15.0 tones per day.