Abstract-A frequently encountered problem in peer review systems is to facilitate pairwise comparisons of a given set of documents by as few experts as possible. In (7), it was shown that, if each expert is assigned to review k documents then r n(n-l )Ik(k-1)1 experts are necessary and r n(2n-k)/Kl experts are sufficient to cover all n(n-l)/2 pairs of n documents. In this paper, we show that, if vn :: k:: n/2 then the upper bound can be improved using a new assignnment method based on a particular family of balanced incomplete block designs. Specifically, the new method uses r n(n+k)/Kl experts where nlk is a prime power, n divides K, and vn :: k :: n/2. When k = vn , this new method uses the minimum number of experts possible and for all other values of k, where vn < k :: n/2, the new upper bound is tighter than the general upper bound given in (7).Keywords-assignment problems, balanced incomplete block design, combinatorial assignment, document evaluation, ordinal ranking, peer review.