The differential cross section for the incoherent scattering of 662-keV gamma rays by the i£-shell electrons of tin, tantalum, and lead was determined by experiment. The scattered photons were selected in coincidence with accompanying K x rays from the scatterer foil, using the Nal(Tl) scintillation detectors and the slow-fast coincidence method. The cross section daic/dtl was compared with that predicted by the KleinNishina formula, daF/d£l, at scattering angles 20°, 35°, 50°, 65°, and 100°. The experimental results show that for all cases with these scatterer elements the cross-section ratio d