Development of efficient methods to improve biological efficiency is a major focus of commercial mushroom growers. The potential of sawdust and rice husk, readily available wastes as casing materials for Pleurotus pulmonarius propagation on ramified cassava peel substrate was investigated. Casing with rice husk and sawdust reduced the time of fruiting over uncased substrates by 23.8% and 21.4% respectively. However, the biological efficiency of production increased only with sawdust casing overlay from 8.53% to 26.67%, while a reduction (6.50%) was recorded with rice husk casing. Utilization of sawdust as a casing material will have both environmental and economic implications.