Egg sales at the country's largest discount store chain E-Mart from Wednesday to Saturday declined 40 percent compared to the same period the previous week, its operator E-Mart Inc. said.
Lotte Mart, another major hypermarket chain, also saw its sales from Wednesday to Friday decline 45 percent during the same period, according to its operator Lotte Shopping Co.
The retailers declined to provide details on the actual amount of revenue.
The country has been gripped by a fiasco over eggs polluted with insecticides.
After carrying out a nationwide inspection, the government said 49 out of 1,239 egg farms in the country had used illegal insecticides, including fipronil.
The same pesticide has been at the center of a massive health scare that erupted in Europe last month.
Despite the government's swift measures to quell public health concerns, the authorities have been criticized for failing to thoroughly carry out the inspection.
Hundreds of farms are undergoing re-examination following suspicions their samples were tested without meeting due procedures. The inspection is scheduled to be completed Monday.