A variable valve train system for an internal combustion engine wherein the engagement section of a transmission mechanism is lubricated by means of an existing part for driving a variable valve actuation mechanism. Gears forming the engagement section of the transmission mechanism are arranged at a position where the engagement section is lubricated with a lubricant scattered from an endless elongate member for driving a camshaft. The transmission mechanism can therefore be lubricated without the need for additional use of a lubricant passage and its associated elements, besides the existing parts for driving the variable valve actuation mechanism.