A prospective study was carried out to determine the prevalence of autonomic dysfunction in patients with lymphoma, and to assess the effect on this of chemotherapy. Twenty consecutive patients presenting with Hodgkin's disease, high-grade non-Hodgkin's lymphoma, or low-grade non-Hodgkin's lymphoma were studied. All had advanced disease, requiring combination chemotherapy which included the use of vinca alkaloids. Clinical assessment and standard cardiovascular autonomic function tests were carried out prior to and following completion of chemotherapy. Although no patients had clinical evidence of autonomic neuropathy at presentation, 16 (80%) had abnormal cardiovascular autonomic function tests. There was no correlation with the presence or absence of mediastinal disease. There was significant improvement in autonomic scores with treatment despite the use of drugs of known neurological toxicity. Some patients showed residual abnormalities of autonomic function despite disease resolution. We suggest that subclinical autonomic dysfunction is common in patients with lymphoma, and probably represents a paraneoplastic syndrome--the pathogenesis and prevalence of which deserve further study. This phenomenon may predispose patients with lymphoma to develop gastrointestinal and genitourinary dysfunction, or postural hypotension, and should be considered during the evaluation of the neurotoxicity of chemotherapy regimens.