In a study conducted at Songklanagarind Hospital in the south of Thailand, the subjects were 225 patients (210 boys and 15 girls) with glucose-6-phosphate dehydrogenase (G6PD) deficiency. Favism was found in 3.6% of the G6PD-deficient children. Approximately one half of the G6PD-deficient patients with favism were younger than 2 years. Sudden onset of anemia was found within 1 to 3 days after ingestion of dried fava beans. The classic features of favism, which are pallor, hemoglobinuria, and jaundice, were detected in all cases. To characterize the known G6PD mutations in Thai children, molecular analysis was performed for 8 G6PD-deficient children with favism by a combination of polymerase chain reaction-restriction fragment length polymorphism analysis and amplification refractory mutation system analysis. The G6PD variants in these children were G6PD Kaiping 1388,G-->A; G6PD Mahidol 487,G-->A; G6PD Viangchan 871,G-->A; and uncharacterized mutation with silent mutation 1311,C-->T.