The effects of nitrogenation on the magnetic properties of Sm2(Fe0.9M0.1)17C1.6 (M=Ga,Cr) melt-spun ribbons were studied. The melt-spun amorphous ribbons are crystallized at temperatures above 550°C, forming a phase with the TbCu7 type structure, and on heating to 680°C and above underwent a further transition to a phase with a Th2Zn17 type structure. Nitrogenation at 550°C for four hours enhances the magnetic properties of annealed ribbons. The Sm2(Fe0.9Cr0.1)17C1.6 ribbon annealed at 650°C, which consists of TbCu7 structure, exhibits a high postnitrogenation (BH)max of 11.0 MGOe. Sm2(Fe0.9Cr0.1)17C1.6 ribbon annealed at 725°C, which consists of the Th2Zn17 structure, shows a high coercivity of 19.0 kOe with a (BH)max of 7.4 MGOe after nitrogenation.