Tokamaks may be efficiently heated at electron cyclotron resonance by launching of the extraordinary wave from the inside of the torus with a simple waveguide aperture. For typical tokamak parameters, 90% of the incident energy is absorbed in one traversal of the resonant surface. There is an effective maximum density for linear heating at the point where the plasma frequency is equal to the cyclotron frequency. The bulk of the plasma electrons is heated, increasing the perpendicular energy with no tendency to accelerate a high energy tail of the velocity distribution. The ordinary wave may be launched from outside the torus with somewhat smaller heating efficiency. Heating rates and velocity diffusion coefficients are presented.