Abstract. Let K = Q(pp;pd) be a real biquadratic ¯eld with p ´ 1 mod 4 or p = 2
and d a squarefree positive integer. The Hilbert genus ¯eld is described explicitly by Yue
([15]) in the case that p ´ 1 mod 4 and d ´ 3 mod 4. In this article we give the Hilbert
genus ¯eld of K explicitly for the remaining cases. We also consider the function ¯eld
analogue of this problem.