We treated 245 strongyloidiasis patients with 7 schedules of mebendazole (MBZ) and obtained the eradication rates at 8 months to 2 years after the final treatment as described follows; MBZ (100 mg) was given twice a day orally. [Square bracket shows incidence of liver disfunction.] 1) The eradication rates at 2 years after single course of MBZ therapy for 28 days and a combination therapy (thiabendazole 500 mg powder form three times daily for 5 days followed by MBZ in powder form for 9 days, repeated once) were 93.8% (15 of 16 patients), [71.4%] and 100.0% (16/16), [50.0%]. 2) The eradication rates at 8-15 months after using MBZ alone in varying dosages were as follows: a) MBZ powder was administered for 5 days and was then repeated 1, 3 and 4 weeks later: 87.1 (27/31), [51.1%]. b) MBZ powder was given for 5 days and repeated 1 and 3 weeks later: 100.0% (7/7), [30.8%]. c) MBZ powder was administered for 4 days and repeated 1, 3 and 4 weeks later: 96.3% (26/27), [57.8%]. d) MBZ in tablet form was given for 4 days and repeated 1, 3 and 4 weeks later: 89.6% (43/48). [66.2%]. e) MBZ in tablet form was administered for 4 days and repeated 1 week later: 69.2% (9/13), [25.0%]. As described above, although the incidence of liver disfunction in the 4-day with 2-course therapy was lower than the other schedules, the eradication rate was lower. From these results, MBZ should be given to strongylodiasis patient for 4 days and repeated once, or for 3 days and repeated two or three times with 1 to 2 weeks intervals.