No data exists in the extant literature regarding the distal swelling of the posterior interosseous nerve (Acrel's ganglion). To further elucidate this ganglion, ten adult cadavers (20 sides) underwent dissection and histological examination of this structure. No inflammatory response was noted in these histologically normal peripheral nerve structures. No neuronal cell bodies were identified. Although the etiology of such swellings is unclear, the term "ganglia" should not be applied to these enlargements of the distal posterior interosseous nerve. © Springer-Verlag 2007.