The asymptotic chi-square test for testing the Hardy-Weinberg law is unreliable in either small or unbalanced samples. As an alternative, either the unconditional or conditional exact test might be used. It is known that the unconditional exact test has greater power than the conditional exact test in small samples. In this article, we show that the conditional exact test is more powerful than the unconditional exact test in large samples. This result is useful in extremely unbalanced cases with large sample sizes which are often obtained when a rare allele exists.