Survey work on sublittoral sediment infauna of Scapa Flow was carried out in April 1986, at 17 sites, using grab samples (a Hunter Grab was used). The sampling strategy used was based upon the stations used in an earlier D.A.F.S. (1975) survey of the area not produced. Both the sediment characteristics and the fauna are described for each station sampled. The stations investigated can be grouped into several units (see report) based upon these sedimentary and faunistic characteristics. A significant observation was the discovery of uniquely abundant populations of the caudofoveate mollusc, Chaetoderma nitidulum. Several new species records for Orkney were obtained and the total species list for the region is also given.