Abstract. Transitions to the improved confinement regimes were studied in T-10 ECR heated tokamak: the H-mode with and without ITB and the pellet enhanced confinement (PEC) regime. It was shown that subtle changes in q profile allows us to obtain either ITB or ETB only, or both of them under approximately similar conditions. H-mode can be obtained by both power increase and pellet injection. In the PEC-mode the averaged plasma density has more peaked profile than in the H-like mode. The confinement time in the PEC-mode is 30% higher than that in the H-like mode. The global confinement in the regime with the density above Greenwald limit under the strong gas-puffing and ECRH was investigated. To identify the type of turbulence responsible for transport, Ohmic and ECRH regimes with variation of qL and gas puffing were considered. Two regions with different turbulence properties corresponding to ITG or DTE and resistive interchange instabilities were observed along the minor radius.