The paper presents the results of an experimental investigation on scour around pile groups with different configurations exposed to waves. Two kinds of tests were carried out: the actual scour experiments, and bed shear stress measurements. Seven kinds of pile-group arrangements were tested, including the side-by-side arrangements of piles, tandem arrangements of piles, and triangular and square group arrangements with two-, three-, and four-pile groups. The variations with the pile spacing as well as the Keulegan-Carpenter number, \IKC\N, were investigated. The scour depth can increase with respect to its single-pile value by as much as a factor of 3 for moderate \IKC\N numbers [such as \iO(10)] for most of the pile-group configurations for small pile spacings. For small \IKC\N numbers, this increase can be even higher, by as much as a factor of 10 or more. For a given pile spacing, the scour depth is mainly governed by the \IKC\N number. In agreement with the single-pile case, the larger the \IKC\N number, the larger the scour depth. The bed was live in all the tests except a few cases.