In a previous study the prevalence of Raynaud’s phenomenon (RP) in patients with idiopathic carpal tunnel syndrome (CTS) was found to be 60% which is much higher than that in the general population. We undertook a further study of the same cohort of patients have both CTS and RP and who had an open release of the carpal tunnel, to observe the effects of the operation on RP. We observed whether the symptoms of RP improved, and repeated the cold provocation tests to see if the arterial pulse which was decreased before operation would recover. We rated the outcome as good when the patients showed both an improvement of the symptoms of RP and a normal pulse amplitude after exposure to cold, fair when the pulse amplitude recovered to more than two-thirds of that before exposure, and poor when cold hypersensitivity was persistent or showed the same degree of decreased pulse amplitude as observed before operation. Of the 18 patients with both conditions, ten (56%) had good and four (22%) fair results, with a mean recovery time of 4.2 months (6 weeks to 1 year) after operation. If the vasospasm seen in RP is an expression of vasomotor irritation in the carpal tunnel, these findings suggest that local compression of vasomotor fibres in the carpal tunnel can also be relieved by the release of this structure. Careful consideration, however, is still required in treating patients with both conditions since in some cases. RP may be superimposed or it may have other origins