An adjustable, stainless steel, head restraining device and small screw-tightened skull clips are described which enable us to record single unit neuronal activity chronically from awake, behaving primates of various sizes. We have used this method of head restraint over the past 4 years on 8 primates, for periods up to 18 months without any mechanical failures. This equipment reduces problems stemming from bone necrosis and is well tolerated.