A best evidence topic was written according to a structured protocol. The question addressed was, in what proportion of patients is the nerve of Kuntz identifiable? A total of 55 papers were found using the reported search, of which six represented the best evidence to answer the clinical question. The authors, date, journal, study type, population, main outcome measures and results are tabulated. The nerve of Kuntz was originally described in 1927 as being a connection from the second intercostal nerve to the first thoracic ventral ramus. Controversy exists as to whether it is present universally and thus whether it should be identified during thoracoscopic sympathectomy. The six studies highlighted involved dissection of the upper thoracic sympathetic chain of adult cadavers with descriptions of the anatomical variations. A study by Cho et al. [Cho HM, Lee DY, Sung SW. Anatomical variations of rami communicants in the upper thoracic sympathetic trunk. Eur J Cardiothorac Surg 2005;27:320-324] suggested that anatomical variation was more common at T2 compared to T3 and T4, of which 60% corresponded to the original description of the nerve of Kuntz. A similar prevalence was found by Marhold and colleagues [Marhold F, Izay B, Zacherl J, Tschabitscher M, Neumayer C. Thoracoscopic and anatomic landmarks of Kuntz's nerve: implications for sympathetic surgery. Ann Thorac Surg 2008;86:1653-1658], who also suggested that open dissection led to significantly easier identification of this anatomy than thoracoscopy. The same authors frequently found that the nerve of Kuntz was associated with a superior intercostal vein located parallel to it, meaning that these subpleural veins may act as an anatomical landmark. In four of the papers where cadavers where dissected bilaterally, variations in the anatomy of the sympathetic chain were not always symmetrical. We conclude that most patients will have some form of variation in the anatomy of their T2 ganglion, which often corresponds to the original description of the nerve of Kuntz. The appreciation of this variation may be more difficult during thoracoscopy as compared to open anatomic dissection.