ABSTRACTVolatile compounds which contribute to the distinct melon‐like aroma of fresh Pacific oysters (Crassostrea gigas) were identified as (E,Z)‐2,6‐nonadienal and 3,6‐nonadien‐1‐ol, but these compounds were not found in the less intensely flavored Atlantic oysters (Crassostrea virginica). 1‐Octen‐3‐one, 1‐octen‐3‐ol, 1,5‐octadien‐3‐one, 1,5‐octadien‐3‐ol, and 2,5‐octadien‐1‐ol were found in both species of oysters, and contributed a characteristic heavy, planty aroma to each. Sensory panel scores for intensity of fresh melon‐like flavors were significantly higher for both raw and steamed Pacific oysters than for comparable Atlantic oysters. Enzymic generation of alcohols and carbonyls that comprise the characterizing aroma compounds from polyunsaturated fatty acids was demonstrated by preventing their formation with specific inhibitors for cyclooxygenase (acetylsalicylic