Studies in human psychoneuroimmunology began around 1919, but a systematic approach wasn't used until the work of Solomon in the 1960s. Recently, the new specialty has achieved relative independence due to considerable data acquisition. Stress research has revealed relationships between neuroendocrine and immune changes. In parallel, increasing evidence of immunological alterations in psychiatric diseases has expanded the field; presently, immunological correlates of psychosomatic diseases and personality are sought. On the other hand, while immunological disease has been psychologically assessed for many years, a clear-cut link between psyche and immunological changes has yet to be shown. This fact, along with the therapeutic implications of advancing knowledge, will influence strongly the future trends of psychoneuroimmunology. Concepts emerging from the study of this field will be of heuristic value to both psychiatry and immunology and will help define new and expanded limits for both disciplines.