The neuro-vascular complex was investigated at the brachial and digital levels in the wings of the flying-fox, Pteropus giganteus (Megachiroptera). Fluorescence histochemistry of the adrenergic transmitter (formaldehyde method) revealed a dense plexus of adrenergic nerve terminals in the adventitia of the main arteries. No fibres penetrated into the muscular media. The pulsating veins received a less well-developed fluorescent plexus which, however, was distributed throughout the muscular wall. Cholinesterase activity was observed in plexuses having the same density and distribution as the catecholamine-storing fibres. The identity of these cholinesterase-containing nerves has been discussed. Transection of the brachial nerve resulted in a pronounced, though not complete, denervation of the vessels examined at the metacarpal level 14 hrs to 6 weeks postoperatively. The results of the denervation experiments are probably related to the finding that the autonomic vascular nerves enter the wing not only via the brachial nerve trunk but also together with the blood vessels.