To assess the concomitance of strongyloidiasis and HTLV-1 infection, an epidemiological survey was conducted in Okinawa, Japan, using the agar-plate culture, a highly sensitive method for detection of Strongyloides stercoralis. No significant difference in the positive rate of anti-HTLV-1 antibody was found between Strongyloides carriers and non-carriers. This result suggests that these two infections occur independently.