Abstract: The problems of multicast routing and wavelength assignment in all-optical networks were studied. Based on wavelength graphs, a multicast routing and wavelength assignment algorithm for wavelength convertible optical networks was presented. The proposed algorithm deals with the routing and wavelength assignment as a unified process, and adjusts the cost of node with a multicast tree dynamically. It can construct a minimal cost multicast tree satisfying delay bound constraints. Moreover, the algorithm avoids the high complexity common to most delay-constrained heuristics.