Abstract. Studies were conducted for 21 days in a solid state fermentation to investigate the impact of fungal treatment on the chemical composition, mineral content and in vitro digestibility of acha straw treated with three species of fungi: (Pleurotus ostreatus, POA; Pleurotus tuber-reguim,PTA and Pleurotus pulmonarius, PPA). The result obtained showed an increase in the crude protein (CP) from 6.28% for the control (untreated acha straw) to 7.69% for the Pleurotus ostreatus treated acha straw (POA), 7.94% for the Pleurotus tuber-regium treated (PTA) and 8.03% for the Pleurotus pulmonarius treated (PPA) acha straw. Contrarily, the crude fibre (CF) decreased significantly (P<0.05) from 35.84% for the control to 30.78% for POA, to 33.28% for PTA and 31.16% for PPA. Similar significant (P<0.05) decrease was also obtained for the cellulose contents of all the fungal treated. The CF fractions (NDF, ADF and ADL) also decreased significantly. The fastest rate (c) of gas production was obtained in POA (0.0334h-1) with the slowest rates in PPA (0.0298h-1) and the control (0.0255h-1). Gas volumes at 24h and 72h were highest in PPA while the highest gas volume at 48h was recorded in PTA. The fermentation of the insoluble, but degradable fraction (b) range from 34 ml (control) to 58 ml (PTA). The estimated organic matter digestibility also increased from 48.34% in the control to 53.71% in Pleurotus pulmonarius samples. The highest values in short chain fatty acid (SCFA) and metabolizable energy (ME) were also estimated for PPA. The result obtained in this study showed decreases of CF and improvement in the CP, and in vitro digestibility after fungal treatment suggesting the possibility of recycling acha straw into value added ruminant feed.