An analysis of heat discharged by thermal fluids along the c. 3000-km-long Himalayan geothermal belt (HGB) shows that heat transfer is concentrated along 30- to 50-km-wide `heat bands' which are associated with at least 600 geothermal systems. The bands have been interpreted as segments of major, concentric slip lines caused by plastic deformation of the ductile crust within the Asian plate resulting from plate collision. Assuming that this crust behaves like an ideal plastic medium, the heat transfer within and along a slip line can be estimated. It amounts to c. 55 mW/m 2 for a 40-km-wide band. Estimates of present-day heat discharges point to 20-35 mW/m 2 for convective, and 10-30 mW/m 2 for anomalous conductive losses (less well constrained) for a heated crustal strip in the greater Lhasa area. Computed geotherms indicate that partial melting can develop at c. 30- to 50-km depth within heat bands. The spatial asymmetry of heat discharged in the HGB (heat bands in the eastern Himalaya transfer about 2-3 times more heat than does the entire western Himalaya) can be explained by a counterclockwise rotational penetration of the Indian into the Asian plate.