Let h greater-than-or-equal-to 2 be an integer. A set of positive integers B is called a B(h)-sequence, or a Sidon sequence of order h, if all sums a1 + a2 + ... + a(h), where a(i) is-an-element-of B (i = 1, 2, ..., h) , are distinct up to rearrangements of the summands. Let F(h)(n) be the size of the maximum B(h)-sequence contained in {1, 2, ..., n] . We prove that F2r-1(n) less-than-or-equal-to ((r!)2n)1/(2r-1) + O(n1/(4r-2)).