A 63-year-old man developed a pleural effusion with marked eosinophilia, which was more prominent in the pleural fluid than in the peripheral blood. The pleural effusion spontaneously disappeared 7 days after admission. A multiple dot enzyme-linked immunosorbent assay for anisakiasis was strongly positive for both the serum and pleural fluid. The serum IgG titre for Anisakis simplex gradually decreased over 7 months. It is suspected that Anisakis larvae can penetrate the alimentary canal, and then migrate into the pleural cavity through the diaphragm. Screening with a serological test is useful in the diagnosis of this condition; human pulmonary anisakiasis.