The aim of this study is to investigate the influence of the use of different types of phototherapy on different lymphocytes subsets CD4 and CD8 in the treatment of hyperbilirubinemia in neonates.

Inclusion Criteria:

Term neonates with a gestational week higher than 37weeks, according to the guidelines of the American Academy of Pediatrics (2004) which stated that gestational ages of newborns are determined according to the first day of the mother's last menstrual period (by the mother's statement) and were additionally confirmed by the Ballard scoring system (Ballard et al., 1991) and antenatal ultrasonographic estimation or obstetric records if present.

• Clinically significant indirect hyperbilirubinemia requiring phototherapy in the first week of life.
• No pathologic etiological factors for hyperbilirubinemia

Exclusion Criteria:

• Total bilirubin level of >20 mg/dl.
• Prematurity.
• Sepsis.
• Congenital anomaly.
• Elevation in direct bilirubin level.
• History of immune deficiency the family.
• History of preeclampsia or any other diseases or drug use of the mother