Trade surplus was 3.37 billion U.S. dollars in August, staying in black since February 2012, according to the Korea Customs Service.
Exports, which account for about half of the economy, edged down 0.2 percent from a year earlier to 46.23 billion U.S. dollars in August.
The slight fall was attributable to less business days compared with a year earlier. Daily average exports increased in August from the prior year.
Shipments of telecommunication devices, including smartphones, advanced 7.7 percent last month, with those for chips, oil products and ships rising 4.8 percent, 6.3 percent and 4.5 percent, respectively.
Exports of automobiles and auto parts declined 18.2 percent and 6.6 percent each on partial strikes by some car manufacturers, and shipments of consumer electronics tumbled 23 percent.
Imports expanded 3.1 percent to 42.86 billion dollars in August on a yearly basis. Demand for raw materials and consumer goods increased, but capital goods import dropped 8.5 percent, reflecting weak investment sentiment among companies