It is proved that a periodic group whose element orders do not exceed 6 either is a locally finite or is group of exponent 5.The spectrum of a group G is the set ω(G) of its element orders. The objective of the present paper is to prove THEOREM. If the spectrum of a group G is equal to {1, 2, 3, 4, 5, 6}, then G is locally finite and satisfies one of the following:(where C is isomorphic to SL 2 (3) or to a group x, y | x 3 = y 4 = 1, x y = x −1 , and C acts freely on N ;(2) T = O 2 (G) is a nontrivial elementary Abelian group and G/T is isomorphic to A 5 ;(3) G is isomorphic to S 5 or S 6 . Hereinafter, O p (G), where p is a prime, denotes the greatest normal p-subgroup of G; A n and S n stand for, respectively, the alternating group of degree n and the symmetric group of degree n. A group A freely acts on a group B if A acts on B, B is nontrivial, and b a = b if a and b are nontrivial elements of A and B, respectively.