The legal Patagonian toothfish (Dissostichus eleginoides) longline fishery operating in the French Exclusive Economic Zones (EEZs) of Crozet and Kerguelen Islands (Subarea 58.6 and Division 58.5.1 respectively) killed 26 668 seabirds between September 2001 and August 2003. Overall, the white-chinned petrel (Procellaria aequinoctialis) was the most frequently killed species, with males being more frequently caught than females. Grey petrels (Procellaria cinerea) were caught accidentally in large numbers over this same period. Giant petrels (Macronectes spp.), black-browed albatrosses (Diomedea melanophrys) and grey-headed albatrosses (D. chrysostoma) were also caught over this period. A multivariate analysis suggests that a combination of factors (environmental and relating to fishing techniques) have an effect on the observed numbers of seabirds caught incidentally. The results of this study suggest that a significant part of the mortality of white-chinned petrels and grey petrels is explained by the time of year, geographical area and type of longliner (manual versus automatic baiting). Almost all of the incidental mortality occurred exclusively during the breeding season, except for giant petrels. The highest mortality of white-chinned petrels, grey petrels, black-browed albatrosses and grey-headed albatrosses corresponded to the chick-rearing period. In addition, the vessels using automatic baited longlines caught many more birds than those using manual baited longlines. Based on the results of this analysis, several recommendations are made with the aim of reducing the incidental mortality of the various species concerned in the French EEZs of Crozet and Kerguelen Islands (Subarea 58.6 and Division 58.5.1 respectively).