Seven Swiss cheeses and the oil soluble, water-soluble volatile, and water soluble nonvolatile fractions isolated from them were evaluated by the flavor profile method. The intensities of nine perceived flavor notes were correlated with analytical values of some flavor components. In the water-soluble volatiles, acidity, sweetness, and lipolyzed flavor were correlated with total free acids, diacetyl, and butyric acid, respectively. Synthetic mixtures of acetic, propionic, and butyric acids, diacetyl, and ammonia reproduced the flavors of the isolated fractions. In the water soluble nonvolatiles, acidity could not be correlated with lactic acid or pH, but it was correlated with the amounts of small peptides and amino acids. The sweetness of the water-soluble nonvolatiles depended on the interaction of calcium and magnesium ions with small peptides and amino acids. Small peptides and amino acids also were responsible for the brothy-nutty flavor of this fraction. The burned and bitter flavor of the water-soluble nonvolatiles was attributed to medium sized (tri to hexa) peptides. The nutty and volatile flavors of the oil solubles were caused primarily by free fatty acids. Neutral oil-soluble compounds seemed to suppress the perception of lipolysis, and in excess to cause an undesirable “fermented” flavor. The flavor of whole cheese could not be predicted from those of its fractions. In whole cheese, sweet, nutty, and volatile flavors correlated with dipeptides, burned flavor with lactic acid, and volatile flavor with acetic acid. The acid flavor correlated with the percentage of water-insoluble fatty acids in the aqueous portion of the cheese.