To clarify the efficacy of repeated stool examinations by the agar plate culture method for the detection of Strongyloides stercoralis infection, 4,071 stool samples collected from 2,406 patients > 50 years of age in Ryukyu University Hospital were examined. The cumulative detection rate of S. stercoralis infection was 4.7% (112/2,406). At the first, second, third, and beyond fourth examinations, the detection rates were 3.6% (86/2,406), 1.5% (12/786), 2.6% (10/392), and 2.0% (4/198), respectively. From these results, the cumulative detection rate was estimated to be 7.4% when three stool samples were examined for all patients. Our study showed that repeated stool examinations increase the sensitivity of detection of S. stercoralis infection.