This study investigates whether exporting is a cause or an effect of high productivity of firms’ in the Korean manufacturing industries. For this purpose, a panel database is assembled with 1335 firms from eight Korean manufacturing industries during 1997–2003. Evidence that high productivity causes exporting, referred to as self-selection, is found in three out of eight industries. However, we do not find support for the hypothesis that high productivity is affected by exporting, except in one industry. Sunk-cost or previous-export-experience effect on the current export status is statistically significant and robust across industries unlike that of firms’ productivity and size.