According to the results of this study, the prevalence ofhaving had STD or genital ulcers was similar to that seen in the previous national survey of the general population in 1990 [16]. This was surprising because other data have suggested declines in STD in Thailand [2,3,15,31]. However, the method for collecting STD data here was more anonymous than that used in the previous national survey [16], which would suggest that the present data may underestimate STD less than previous research using face-to-face interviews.