Twenty patients complaining of symptoms deriving from their amalgam fillings and non-patient group were assessed by means of the perceptual projective Defense Mechanism Test (DMT). The test protocols were scored for 130 DMT variables and analyzed by means of the multivariate statistical method Partial Least Squares discriminant analysis. The objective was to try to distinguish die group with amalgam illness from the non-patient group by means of the DMT. The results showed that it was possible to distinguish the two groups significantly from each other. The most characteristic traits of the patient group were general lateness in perception and few emotional responses compared with the non-patient group and, especially, an inability to perceive die aggressive component in the stimulus picture. The DMT seems to be powerful method in the effort to understand the mechanisms underlying the problems of amalgam illness.