Exports rose 8.2 percent year-on-year for the first 20 days of March, and 5.1 percent for the whole month.
The April reading was higher, however than the 2.2 percent rise in exports for the January-March quarter.
South Korea is the world's seventh-largest exporter and is the first major exporting economy to report foreign trade figures each month, providing an early clue on the state of the global economy.
Exports for the April 1-20 period totalled $30.669 billion.
Imports stood at $28.903 billion, a 3.2 percent drop from a year ago, the data from the Korea Customs Service data showed.
The April data brings the trade surplus for the 20-day period to $1.766 billion, according to a Thomson Reuters calculations.
China is the largest export market for South Korea, taking in around one-quarter of total overseas shipments. Other major export markets are the United States and the European Union.