A mechanism for cooling the platform for the drive blades of a gas turbine uses a simple configuration which reliably cools the platform. The mechanism includes cooling channels in the interior of the platform which open out from one of the cooling air channels for cooling the turbine blades and which exit the platform through the edge nearest the tail. Cooling channels in the platform open out from the entrance to blade cooling channels, travel from the head of the blade along the blade sides, and exit through the edge near the tail of the blade. This structure diverts a portion of the cooling air entering the blade from the cooling channel in the base in order to cool the platform. Cooling air channels may extend from an enclosed air space below the platform to the upper surface of the platform at the front or rear side of the blade. Air channels may also extend on the rear of the turbine blade obliquely from the underside of the platform to the trailing edge of the platform. These channels or combinations thereof constitute a cooling structure through which air can flow to cool a platform for the drive blades of a gas turbine in an efficient and effective manner.