Disclosed is a pharmaceutical composition comprising at least 95%, by weight of all fatty acids present, ethyl eicosapentaenoate (ethyl-EPA) and a capsule shell comprising at least one plasticizer comprising a hygroscopic plasticizer and a film-forming material which does not include chemically modified gelatin, wherein the composition has a baseline peroxide value not greater than 5 meq/kg and upon storage of the composition at 25 °C and 60% RH for a period of 6 months, the composition has a second peroxide value not greater than 8 meq/kg, wherein the hygroscopic plasticizer comprises glycerol and the film-forming material comprises gelatin, and wherein the capsule shell has a weight ratio of gelatin to glycerol of about 2.5:1 to about 10:1.
