A subgroup H of a group G is said to be c-supplemented in G if there exists a subgroup K of G such that G = HK and H∩K is contained in coreG(H).In this paper we prove that a group G is p-nilpotent if every maximal subgroup of P is c-supplemented in G and (|G|, p - 1) = 1, where p is a prime factor of the order of G and P is a Sylow p-subgroup of We also give a condition for a group to be p-nilpotent by using the 2-maximal subgroups of the Sylow p-subgroups.