Survival of naturally occurring larvae of Anisakis simplex in fresh arrowtooth flounder (Atheresthes stomia) was determined after storage for specified periods at four freezing temperatures. All larvae were killed by 96, 60, 12, and 9 h at temperatures of -15, -20, -30, and -40 degrees C, respectively. The average percentages of live larvae per fillet at the next shortest holding time were as follows: 72 h at -15 degrees C, 0 to 3%; 48 h at -20 degrees C, 11 to 30%; 9 h at -30 degrees C, 5%; and 6 h at -40 degrees C, 0 to 3%. Larval survival was directly related to fillet thickness or weight (P < or = 0.05). Larval death was directly correlated to freezing temperatures. Holding time necessary to kill larval nematodes decreased as storage temperature decreased.