Four cases of transient anisakiasis in northern California acquired by ingestion of raw fish were reported to health authorities between May 1977 and June 1980. A single Phocanema decipiens-like 4th-stage (L4) larva was identified in each of two cases. A recently molted adult male P. decipiens with a fragment of attached L4 cuticle and prominent caudal papillae was recovered from a third person. The latter is the only human case known in which an anisakid worm developed to the adult stage was involved. Two Anisakis type I larvae were recovered in the fourth case, being the first parasitologically confirmed case of human infection with this worm described from the coterminous United States. Differential diagnosis was based on cuticular characteristics of larval types and stages as well as the presence of major internal organs. All infections were acquired during May and June. Subjects were 25–37 years old; three were female; two were of Japanese and one of Polynesian ancestry. Raw salmon or raw “red snapper” (probably Sebastes sp.) was the presumptive source of worms in one case each. Mild stomach pain and nausea were noted from the time of ingestion for up to 20 hours after the infective meal; worms were coughed up or found in the mouth up to 2 weeks thereafter. Five other incompletely documented California cases are discussed.