The disassembly line balancing problem is studied under uncertainty. Disassembly task times are assumed random variables with known probability distributions. An AND/OR graph is used to model the precedence relations among tasks. The goal is to assign the disassem- bly tasks to workstations while respecting precedence and cycle time constraints. The objective is to minimize the total line cost including the incompletion cost arising from tasks not completed within the cy- cle time. A stochastic linear mixed integer programming formulation is developed.