This study aimed to estimate the efficiency of fungal pretreatments applied to wheat straw on improving CH4 production. Strains of Pleurotus ostreatus, Phanerochaete chrysosporium, Trametes versicolor were incubated with sterilised straw at 25°C during 30 days. Cellulose, hemicellulose and lignin contents of the straw were respectively 40.1, 42.7 and 6.3%. For P. chrysosporium and T. versicolor assays, 30-35% of the volatile solids (VS) were lost whereas for P. ostreatus assays, 15 to 20% of the VS were not recovered. The BMP decreased between T0 and T20 days and then remained stable (ie., 239 NL CH4 /kg VS). The decrease between T0 and T10 days is correlated with an increase of the soluble fraction of the VS. These results suggest that inhibitory compounds or by-products of hemicellulose degradation may interfere with the anaerobic digestion process. Fungal pretreatments before anaerobic digestion seem not relevant to improve the biodegradability of substrates containing low level of lignin.