The quality of the professional–patient relationship in the treatment of mental illness predicts patient outcome. Hence, we conducted a review of recorded professional–patient communication to identify existing research, methods, and findings. Sixteen studies focused on (i) how psychiatric symptoms are manifested in patient communication; (ii) the role of therapist communication in patient improvement; (iii) the influence of sociodemographic characteristics on doctor–patient communication; and (iv) how patients and professionals jointly construct therapeutic interactions. The findings were disparate and included (a) patient nonverbal communication is impaired in depression and schizophrenia; (b) the use of specific therapeutic skills led to improvement in depression; high expressed emotion (criticism and emotional over-involvement) in treating schizophrenia was a state rather than trait characteristic of therapists; (c) patient gender, income, and education influenced communication about depression, anxiety, and medication; and (d) psychiatrists' varying institutional agendas, which sometimes competed with patients' agendas, strongly shaped their consultations. Few studies investigated two-way professional–patient communication, with most focusing on either patient or therapist communication in isolation from the other. Finally, methodological advances in linking communication processes with treatment outcomes in large-scale observational studies and trials are a challenge for research on medical communication.