A preliminary survey of the prevalence of HTLV-I antibody during 1987 and 1988 in Belgium revealed no positive results among selected blood donors who sided for some length of time in areas where HTLV-I/HTLV-II is endemic (n = 270), in development-aid workers (n = 145), or in missionaries (n = 35) serving in developing countries. Among foreign groups, African students (n = 212), and political refugees (n = 311), HTLV-I/HTLV-II antibodies were detected and confirmed in 3 cases. Limited data from 1987 and 1988 suggest that HTLV-I/HTLV-II poses no major public health problem in Belgium.