Both neutrophil margination and increases in the non-invasively assessed parameter, isovolumetric venous congestion cuff pressure ( P v i ), are symptomatic of some inflammatory diseases. Neutrophil margination occurs primarily, though not exclusively, at the post-capillary endothelial surface. The local haemodynamic changes resulting from margination may be responsible for the observed increases in P v i . Smoke inhalation has been shown in animal studies to cause an increase in post-capillary neutrophil margination by mechanisms that can be blocked by oral vitamin C administration. We looked for indices of a relationship between margination and P v i in man, using cigarette smoke inhalation as a pathophysiological challenge. We also examined the effect of prophylactic vitamin C on the response. Smoke inhalation was associated with highly significant increases in both P v i and heart rate. After vitamin C pre-treatment, no increase in P v i was observed in response to the smoke inhalation; however, whilst heart rate still increased significantly, the duration of this response was attenuated. The results suggest that vitamin C affords protection against some of the cardiovascular and microvascular changes associated with cigarette smoke inhalation in man. They also support the notion that non-invasive assessment of changes in P v i may provide a measurable index of systemic changes in inflammatory conditions.