The Ni-catalyzed, direct arylation of C(sp(3))-H (methyl and methylene) bonds in aliphatic amides containing an 8-aminoquinoline moiety as a bidentate directing group with aryl halides is described. Deuterium-labeling experiments indicate that the C-H bond cleavage step is fast and reversible. Various nickel complexes including both Ni(II) and Ni(0) show a high catalytic activity. The results of a series of mechanistic experiments indicate that the catalytic reaction does not proceed through a Ni(0)/Ni(II) catalytic cycle, but probably through a Ni(II)/Ni(IV) catalytic cycle.