The two-dimensional strip packing problem consists of packing in a rectangular strip of width 1 and minimum height a set of n rectangles, where each rectangle has width 0 < w <= 1 and height 0 < h <= hmax. We consider the high-multiplicity version of the problem in which there are only K different types of rectangles. For the case when K = 3, we give an algorithm providing a solution requiring at most height 3/2hmax + ε plus the height of an optimal solution, where ε is any positive constant.