Growth stresses are characteristic of normal growing trees and occur in both hardwoods and softwoods. Growth stresses are not visible and can not be measured directly. However, theyare estimated by strain measurements in wood. Growth stresses release when trees are felled, cut into logs and processed into lumber. As a result, splits, cracks and warps occurs in wood materials. Growth strains cause losses in the economic value of wood and create negative effects on wood usage. This paper reviews the nature, formation and manifestation of growth stresses.