The $US5 million dollars is part soft loan and part grant.
It is the second stage of a three part programme for the 'Building Macroeconomic Resilience Program for Tonga'.
A principal economist, Ananya Basu, said the Tonga government is undertaking important policy reforms to strengthen public financial management, promote healthy lifestyles, and improve the performance of state-owned enterprises.
Ms Basu said the ADB program will help further improve the country's fiscal position and business environment.
Photo: Matangi Tonga/ Peter Poulsen Tonga prepares for arrival of the Queen Mother
Source: Radio New Zealand