The objectives of this study were to consider the rate of exchange transfusion (ET) in the newborns at King Chulalongkorn Hospital, Bangkok, from 1994 to 2003, and to evaluate its morbidity and mortality. One hundred and sixty five neonates underwent 183 episodes of ET: In-housed fullterm had ET performed at a younger age than the readmitted/referred infants (72.2 +/- 30.9 vs 150.2 +/- 90.7 hours, p < 0.001), and the in-housed preterm neonates (85.4 +/- 36.7 hours, p < 0. 05). They also had lower mean TsB than those of the readmitted/referred infants when ET was initiated (21.8 +/- 2.1 vs.26. 0 +/- 5.1 mg/dL, p < 0.001). Preterm needed phototherapy after ET longer than fullterm neonates (5.3 +/- 3.2 vs 3.3 +/- 1.7 days, p < 0.001). ABO incompatibility (21.3%), G6PD deficiency (13.4%), both conditions (6.7%), and others (22.2%) were identified as causes of hyperbilirubinemia. Unknown causes accounted for 36.4%. There was no mortality in the present study. Overall rate of morbidity was 15.3% of which 67 percent was infection associated conditions. Preterm suffered additional complications of anemia, apnea and cardiac arrest. Sick infants (31.3%) were more likely to develop complications than healthy ones (6.8%). In the healthy group, preterm were more likely to develop morbidity than fullterm neonates (p = 0.0016), while no significant difference was identified between them in the sick group (p = 0.8). ET causes high morbidity, therefore, it should be initiated only when the benefit of preventing kernicterus outweighs the complications associated with the procedure.