An automated program using a Finapres device and a personal computer, using a battery of five cardiovascular reflex tests has been developed. This has been used to study cardiovascular autonomic dysfunction in 23 ambulant patients with Parkinson's disease, without disabling fluctuations, and 23 age-matched healthy controls, as a screening method to detect autonomic dysfunction. In one patient only a Finapres signal of insufficient quality due to the tremor excluded subsequent analysis. Heart rate response to forced breathing was abnormal (below the fifth percentile of 124 normals) in six (26.1%) of parkinsonian patients and in one (4.3%) healthy age- and sex-matched control, to standing up four (17.4%) versus none, and to the Valsalva manoeuvre seven (30.4%) versus two (8.7%) respectively. The blood pressure response to standing up was abnormal in two (8.7%) parkinsonian patients and in none of the controls, while the response to sustained handgrip was abnormal in five (21.7%) patients versus one (4.3%) control. Autonomic dysfunction is commonly defined as an abnormal score on two or more of the five tests. Using this arbitrary definition, five patients with Parkinson's disease (= 23%) had cardiovascular autonomic dysfunction, and none of the controls were abnormal.