Favism, a hemolytic condition associated with fava bean consumption among the glucose-6-phosphate dehydrogenase (G6PD) deficient persons, is well described in the Middle East and Mediterranean areas. However, it is not well documented among the Thais or other Southeast Asians. It is possible that it does exist but that hemolysis which develops is of very minor degree and thus escapes clinical detection. This cross-sectional study hypothesizes that if the fava bean and G6PD deficiency interact in the Thai population, they should cause a significant difference in hematocrit level. The study was carried out in a community hospital in a malaria endemic area. We found that there was a trivial difference of the hematocrit (approximately 1%) which was too small to warrant any clinical significance after controlling for the extraneous effects of age, sex, use of malaria chemoprophylaxis, falciparum infection, use of analgesics/antipyretics and admission status of the patients (p = 0.668). This may be due to the presence of different G6PD mutants to those found elsewhere or due to different consumption patterns of fava beans among the Thais compared to people in other areas with high prevalence of G6PD deficiency.