In substrates with Se concentrations greater than 12.8 mg kg1, mushrooms possessed larger stipes and smaller caps than in media without Se or with low Se concentrations (Fig. 1). In addition, an unpleasant smell was observed in mushrooms cultivated in substrates with Se concentrations higher than 25.4 mg kg1. The shape alterations of the P. ostreatus mushrooms differed from those observed in Lentinula edodes, which did not present any differences in the cap and stipe diameters and stipe length when enriched with Se ( Nunes, 2005). However, those authors observed darker caps in Se-enriched mushrooms.