A century ago, an English psychiatrist, Henry Maudsley, wrote of the complexity of somatic and psychic connections in these terms: ‘The sorrow that has no vent in tears makes other organs weep’. Fritz Zorn, the author of a literary work, the novel Mars, published in 1977, shared this intuition: a young man from Swiss upper middle class society, Mars, develops a malignant tumour. This discovery throws his life into turmoil and he says, ‘The tumour represents hidden tears’. This brief chapter discusses four propositions: I — that psychic state is a clear component of immunological well-being; II — that stress, anxiety and depression modify cellular and humoral immunological defences; III — that neurotransmitters, neurohormones or cellular lymphokines play a major role in regulating immunological self; IV — that psychotropic drugs may modify some aspects of immunity. Scientific proof for defending these assertions differs considerably; few seem firmly verified, while many are under discussion. The expression of immunological ecology refers to biopsychosocial interactions and rules out any hypothesis of linear causality. Several thousand million cells, more than the cerebral nervous system contains, form the immunological network. Immunological cell specialization, competence and relations with other systems of the organism are numerous.