In this paper a preliminary analysis was performed on composition of catches obtained by longline fishing in the Mediterranean Sea during fishing seasons of two years May-June in 1995 and late April-early July in 1996. The results showed that species of catches which often appeared were bluefin tuna Thunnus thynnus (Linnaeus), swordfish Xiphias gladius Linnaeus, blue shark Prionace glauca (Linnaeus, 1758), oceanic sunfish Molo molo (Linnaeus, 1758 ) and Atlantic loggerhead turtle Caretta caretta caretta (Linnaeus, 1758). The species of catches which rarely appeared were shortfin mako Isurus oxyrinchus Rafinesque, 1810, Albacore Thunnus alalunga (Bonnaterre ), bigscale pomfret Taractichthys longiPinnis (Lowe) and a kind of rays (Dasyatidae). In the catches bluefin tuna is a predominant species, accounting for 81. 0% (1995) and 66. 9 % (1996). As for the other species including swordfish, blue shark, oceanic sunfish and Atlantic loggerhead turtle were considerably low in proportion.