A sea and air search was continuing for 12 crew still missing from the "Sinegorye".
The vessel, carrying timber and 18 crew, disappeared in the Sea of Japan (East Sea) after sending an SOS on Monday, according to the Russian transport ministry.
Early on Tuesday, South Korea's coastguard said that four sailors had been saved and that one body was found.
Russia's transport ministry later said in a statement that a fifth crew member had been rescued alive and was aboard a South Korean search vessel. He was described as being in a serious condition.
Two patrol boats and one aircraft were searching an area 50 miles (80 kilometres) off South Korea's eastern port of Samcheok.
The China-bound vessel had suffered storm damage, the Russian transport ministry said, adding that the rescue had been delayed by bad weather.

Copyright AFP (Agence France-Presse), 2006