Technical Abstract: Shiitake (Lentinula edodes (Berk.) Pegler) mushroom production in the United States has increased greatly over the last twenty years. Additional expansion of the shiitake mushroom market should be possible if the product can be marketed as a functional food, i.e. a food that has health-promoting effects beyond its nutritional value. High molecular weight polysaccharides (HMWP) including lentinan in shiitake may promote human health. This study was conducted to determine if management protocols influence the HMWP of shiitake mushrooms. Results indicate that measuring the total carbohydrate content of water extractable, ethanol insoluble polysaccharides was a simple way to estimate HMWP. Results also indicate that log-grown shiitake contained more were HMWP than did substrate-grown shiitake. Among log-grown shiitake, both spawn sources and tree species influenced HMWP content. The results suggest that there is considerable variation among shiitake mushrooms in HMWP content and that the protocols used to produce mushrooms influence their HMWP content.