In this paper we study reducibility of those representations of quasi-split
unitary p-adic groups which are parabolically induced from supercuspidal r
epresentations of general linear groups. For a supercuspidal representation
associated via Howe's construction to an admissible character, we show tha
t in many cases a criterion of Goldberg for reducibility of the induced rep
resentation reduces to a simple condition on the admissible character.