On the basis of current studies, polyaryletherketone (PAEK) polymers appear to be materials with great prospects for medical application. The most important member of this family of semi-crystalline thermoplastics is polyetheretherketone (PEEK) with its composites. The excellent properties of this material find their use in the treatment of various disorders of the skeletal system. At present they are used with advantage to construct spinal implants, and replacements for other orthopaedic applications and for dental and trauma medicine are at advanced stages of clinical testing.