The management of old growth forest is challenging issues. Thus, the scientific forest management system has been initiating to produce the quality timber to meet the demand of local people and generate the revenue. Especially Shorea robusta is the most valuable timber species but due to hollow and shake defect, timbers are very poor quality. At the same time, old and over mature trees hinders the growth of regeneration and intermediate storey plants. Therefore, this study was objectively carried out to list out the type of hollow and shakes defects in log, assess timber and economic loss due to these defects. The 1A and 2A felling series of block A of Devdah collaborative forest, Ruandehi Nepal was selected as study site. Altogether 215 defected trees measured in both felling series. Next, diameter of two ends and mid-point of log including defected sections and their lengths measured. Formal and informal interview organized with local people including district forest technicians to know causes and types of defects. Volume of defected timber was calculated subtracting net volume from whole volume of log. The economic loss was estimated multiplying defected section of timber with its price. The result showed that shake, canker and hollow are major defects of loss of timber. There two types hollows in logs particularly partial and whole. Meanwhile, the shakes are cup, ring, heart, star and radial. The highest volume loss was 354.34 and 433.7 cubic feet (cft) in Shorea robusta at felling series 1A and 2A respectively. The highest economic loss was US1557.93inShorearobustacausedbydegradationtoclassBfromA.TotalmonetarylossUS 5804.27 in felling series 1A in Shorea robusta while it was US$ 8365.11 in felling series 2A in same species. This research will be useful for evaluation of forest stand.Keywords: Shake, log, timber, hollow, fellin