This study was carried out to examine the proximate and mineral contents of an edible mushroom, P.sajor-caju in Ekiti State, Nigeria at different stages of development. The mushroom was cultivated on sterilized wood shavings and the fruit bodies were harvested at four stages corresponding to 7, 21, 35 and 49 days after fruiting. The proximate and mineral contents of the mushroom were determined using standard methods. After forty nine days of fruiting, the contents (%) of moisture and crude fiber increased from 90.47 to 94.00 and 0.06 to 0.21 respectively while the contents of protein, fat, ash, carbohydrate and energy (kcal/100g) reduced from 1.21to 0.74, 0.1 to 0.08, 1.07 to 0.69, 7.09 to 5.97 and 32.33 to 25.71 respectively. The mushroom exhibited different variation patterns in their mineral contents with advancing age. The contents (mg/100g) of Mg, Fe and Cu decreased with age while that of K, P, Ca and Zn increased with age. Age had no effect on the content of Mn. This suggests that the recommended harvesting stages would be determined by the particular mineral deficiency being addressed. However, results of the proximate analysis suggest that the mushroom should be harvested early in order not to compromise the nutritional quality.