A survey on anemia and parasite infection was conducted at Khonkaen district, Thailand. The number totaling about 1000 was examined. Physical examination revealed that hypertension and obesity were extremely rare and also that anemia and symptoms of the gastrointestinal tract were common. Hookworm infection was prevalent (67.5%). Anemia was seen in 31%. Judging from hemoglobin levels, 36.4% of children below 6 years, 35.1% of children 6-14 years, 14.2% of adult males, 36.5% of adult nonpregnant females and 36.4% of pregnant females had anemia respectively. Hypochromia and microcytosis were frequently seen in the blood smears. Eosinophilia was also marked in all age and sex groups. Serum iron levels and % saturation of transferrin were low in high percentage except in adult males. In regard to serum vitamin B(12) and folic acid, low values were scarecely observed in all groups. Megaloblastic anemia was not detected at all. Total serum protein was relatively low (though within normal limits) in children below 6 years. It can be said that the anemia is due to iron deficiency in almost every cases in this district and vitamin B(12) and folic acid do not contribute to the anemia. Protein deficiency may play some role for the anemia of children below 6 years.