A method and an apparatus for cutting boards from tree trunks in which transverse cuts are made in a tree trunk which extend into the trunk a predetermined depth and thereafter longitudinal cuts are made into said trunk, which cuts pass through a plane passing through the inner ends of the transversal cuts, whereby the boards are separated from the trunk. The apparatus for cutting boards from tree trunks comprises guide rollers for advancing a trunk in a longitudinal direction, saw units adapted to move in a vertical and in a longitudinal directions to produce the transverse cuts and saw blades movable in the longitudinal direction to produce the longitudinal cuts after the transversal cuts have been made.