We report two cases of toxocariasis with eosinophilic pleural effusion. Case 1: During the 5 months before a 66-year-old man visited our hospital, increases had occurred in eosinophils and CRP level, and a left pleural effusion had developed. Although the left pleural effusion had improved without treatment, on the patient's visit to our hospital it had recurred and pneumonia had developed. Pneumonia was improved by antibiotic therapy. One month later, left pleural effusion had improved without treatment, but right pleural effusion had developed. Pleural effusion revealed that eosinophils were accounting for 42.0% of the cellular components. Immunological examination, including multiple-dot ELISA, showed a high optical density of specific antibody against Toxocara in both the serum and pleural effusion. Case 2: Three weeks before visiting our hospital, a 36-year-old man was diagnosed as having bacterial pleurisy, and antibiotics were started. But pleural effusion had not improved on the patient's visit to our hospital. Pleural effusion revealed eosinophils accounting for 67.5% of the cellular component. Immunological examination, including multiple-dot ELISA, showed a high optical density of specific antibody against Toxocara in the serum. In these two patients diagnosed as having toxocariasis, albendazole was used for 7 weeks in Case 1 and for 8 weeks in Case 2, and pleural effusion improved in both. Three months posttreatment, the optical density of the specific antibody against Toxocara in the serum had also improved. Toxocariasis is an important consideration in the differential diagnosis of eosinophilic pleural effusion.