King oyster mushrooms (Pleurotus eryngii) were divided into three parts: large fruiting bodies (LFB), small fruiting bodies (SFB), and the base. LFB comprised 79.90% of total weight, whereas the base comprised 15.47%. Volatile compounds found were 3-octanone, 1-octen-3-one, 3-octanol, 1-octen-3-ol, benzaldehyde, 1-octanol, and 2-octen-1-ol; the major compound in LFB and SFB was benzaldehyde. Both LFB and SFB contained high amounts of total free amino acids. Sweet and bitter components were comparable in the three parts, whereas monosodium glutamate-like components were high in LFB and SFB. Six 5‘-nucleotides were found in three parts, of which 5‘-cytosine monophosphate was the highest. Flavor 5‘-nucleotide contents in LFB and SFB were comparable and higher than those in the base. In this study, LFB and SFB were similar in their proximate compositions, volatile compounds, and taste components. Keywords: Pleurotus eryngii; king oyster mushrooms; flavor; volatile compounds; soluble sugars; free amino acids;...