It has been established that hemoglobinopathies are widespreat in Southeast Asia, this being particularly well documented in Thailand (Wasi et al., 1969). It appears, however, that for technical a n d / o r geographical reasons, the incidence of these diseases, including the various subtypes of thalassemia, could be still higher in Laos (Baup, 1964). The prel iminary report of a 4-year investigation has recently been published (Sicard et al., 1978). As a consequence of multiple combinat ions o f abnormal genes, such as H b E , and various aand fl-thalassemias, a wide spectrum of syndromes is encountered, ranging f rom asymptomat ic heterozygotes to lethal hydrops fetalis. These associations sometimes raise difficult diagnostic questions. Fur thermore , the increased gravity of most o f tile associated forms constitutes an impor tant public health problem in Laos. Dur ing this investigation, an at tempt was made to use multiple approaches, i.e., clinical, hematologic, genetic, and biochemical, to allow unders tanding and characterizat ion of the observed patterns.