Studies were made on thk effect of repeated harvesting on the growth of Sargassam cristaefolium, S. ilicifolium, S. polycystum, S. wightii and Turbinaria conoides occurring at Mandapam coast for a period of 2 years during June 1986 to November 1988. The growth of these algin yielding seaweeds depended on the period of harvesting and interval between one harvest and next. The maximum standing crop with plants of maximum stature was found during the period September to January in these brown algae. An interval of 7 months is required for the regrowth of these plants to harvestable size and the suitable season for commercial exploitation of these algae is September to January.