In a survey of 351 chronically hospitalized adult psychiatric patients, clinical evidence of irregular respiration compatible with respiratory tardive dyskinesia was present in eight subjects (2.3%). In four, audible involuntary respiratory noises were present. All patients with respiratory irregularities had a facio-bucco-lingual dyskinesia and in four the dyskinesia also involved extremities and/or other regions of the body. The prevalence of respiratory irregularities amongst patients with tardive dyskinesia was eight out of 108 (7.4%); none of the patients without tardive dyskinesia had respiratory irregularities. The prevalence of respiratory irregularities was significantly greater in patients with an organic mental disorder (11.1%) compared with those without (1.3%) (P less than 0.005). None of the patients complained of their respiratory symptoms and none had been diagnosed as having a respiratory dyskinesia prior to the survey. In two patients the symptoms were severe, leading in one case to prominent gasping, dysphagia, severe choking when eating, and episodes of aspiration pneumonia. In a second patient the noisy respiration was interpreted as attention-seeking and intimidating behaviour which led to rejection by the staff. In the remaining six patients respiratory symptoms were relatively minor.