Transformation of a wind wave spectrum through a region of nonuniform current is investigated. It is shown how an evolution equation for the spectral action can be arrived at by the scaling arguments introduced by Phillips (1985). A numerical model based on this equation is applied to two different current systems (a head-on current and a shear current). The model also contains an indicator of excess wave breaking activity. It is pointed out that the short wave part of the spectrum (less than 10 cm, say) is not expected to be well predicted by models like the one presented here. This is probably because excess wave breaking of the longer waves is expected to generate short waves or short-scale surface roughness, an effect not accounted for in these models. ¿ American Geophysical Union 1990