Addressing the need for research on the nature of refractoriness to antipsychotic drug therapy exhibited by a substantial minority of schizophrenic patients, Philip R.A. May and Sven Jonas Dencker instigated an international study group to discuss this problem, beginning with the International Congress of Neuropsychopharmacology in Göteborg, Sweden, in 1980. The study group subsequently met in Haar, Federal Republic of Germany, in 1985; in Banff, Canada, in 1986; and again in Telfs, Austria, in 1988. The study group set three objectives: (1) to clarify the concept of treatment resistance or refractoriness; (2) to suggest criteria for defining or rating the degree of treatment refractoriness; and (3) to explore the role of psychosocial and drug therapies in increasing the responsiveness of the treatment refractory patient. This position article represents a distillation of the study group's efforts to define treatment refractoriness in schizophrenia.