The third plane, took off from the Ramenskoye airport near Moscow, will deliver an airmobile hospital and a group of doctors and rescue workers, a ministry spokesperson was quoted as saying by Russian news agencies.
The emergencies ministry said the hospital has beds for up to 50 patients and is entirely self-sufficient.
Two Russian airplanes with rescuers, sniffer dog teams and emergency vehicles on board had earlier headed to Haiti.
A 7.3-magnitude earthquake jolted Haiti on Tuesday, crushing thousands of buildings, including the presidential palace and the UN peacekeeping headquarters. Over 100,000 people are feared dead in the disaster.
Editor: Zhang Xiang