This document describes the Spanish deep-sea fishery performed in international waters on the Hatton Bank and proximities (NE Atlantic) during the period 1996-2000. This is a multi-species fishery, carried out by stern bottom trawlers, mainly between June and September, in depths mainly between 800 m to 1600 m. The importance of the fishing activity in this area is increasing notably. This fishery has been monitored since the beginning in 1996, with the collaboration of the fishing industry, by means of a scientific observer programme. The observers on board provide data on catches, discards, location and depth, haul by haul. Length samples of the main species and biological material are also collected. The species composition of the catches is presented. In terms of weight, the roundnose grenadier (Coryphaenoides rupestris) and the bairdii smoothhead (Alepocephalus bairdii) are the most important species in the catches. Other less important species are the Portuguese dogfish (Centroscymnus coelolepis) and the blue ling (Molva dypterygia). In addition to the total catch, the composition of the retained catch and the discard are studied. For the main retained species, the dressing types are described and the conversion coefficients are presented. The length distribution of the catches and the discards, length-weight relationships and other biological aspects of some of the main species are analysed.