A global resurgence of yaws in developing countries highlights the need for reliable diagnostic criteria for this neglected infection. We conducted a clinical and serologic survey of 233 children less than 15 years of age who had clinically suspected yaws. A total of 138 (59%) cases were confirmed serologically, and 10 of 12 primary stage cases showed positive results for Treponema pallidum by a polymerase chain reaction assay that has not yet been validated for identification of yaws. A high proportion of cases (46%) were in the secondary stage; 92% of them had osteoarticular involvement, and only 24% had a Venereal Disease Research Laboratory titer greater than 1:32.