We consider the problem of allocating buffer storage to unbalanced ser
ial production lines so as to maximize steady-state throughput. We foc
us on the three-station line whose processing time probability distrib
utions differ in either or both mean and variance. We develop rules of
thumb for the optimal placement of buffers, and demonstrate the count
erintuitive result that a balanced or nearly balanced buffer allocatio
n is optimal for many highly unbalanced lines. We also demonstrate tha
t an imbalance in means has a greater impact on buffer allocation than
an imbalance in variances. Finally, we explore the extension of these
results to the general serial line.