The electronic transport properties of chalcogenide glasses of the type Ge-Se and Ge-Te to which foreign elements such as Bi, As, Cu and In are added, were investigated. Glasses of the (GeSe3.5)100-xBix system show a transition from p to n-type conduction at x ≈ 7 at. % Bi as evidenced by thermo-power measurements. The sign of the Hall coefficient is negative. This feature reveals the possibility of altering the density of charged dangling bonds by the incorporation of foreign additives. The conductivity of GeTe6 glasses is little affected by the addition of As, Cu and In. The thermopower is positive