ABSTRACT: CASE:A 7-week-old came with complaints of not gaining weight yellowish discoloration of body and lethargic, no h/o fever, vomiting , loose stools. no h/o previous hospitalization. birth history: 2.8kg normal vaginal delivery cried immediately after birth no h/o nicu admission. h/o bottle fed with formula feeds. On physical examination, his weight is 3.7 kg (<5th percentile), length is 55 cm (25th percentile), and head circumference is 39 cm (25th-50th percentile). Vital signs are: temperature 98.2°F (36.8°C), heart rate 159 beats/min, blood pressure 75/51 mm Hg, and respiratory rate 36 breaths/min. The baby is thin, jaundiced, and pale but is alert and cooing. He appears severely dehydrated, with delayed capillary refill of 3 seconds. There is no rash, petechiae, or organomegaly. Laboratory evaluation shows total bilirubin of 15.2 mg/dL (259.98 mmol/L) and conjugated bilirubin of 0.5 mg/dL (8.55 mmol/L). Complete blood cell count reveals a white blood cell count of 7,600/mL (7.6 x 109 /L), hemoglobin of 7.6 g/dL (76 g/L), hematocrit of 22.6% (0.226), platelet count of 251 103 /mL (251 x 109 /L), mean corpuscular volume of 84.7 mm 3 (84.7 fL), and red cell distribution width of 18.3%. Urinalysis is negative for blood, leukocyte esterase, nitrites, and reduc-ing substances. Urine and blood cultures are obtained. The newborn screening result is checked and is negative for congenital hypothyroidism but reveals homozygous sickle hemoglobin (Hgb SS) consistent with sickle cell disease (SCD). Additional evaluation leads to the cause of his pallor and jaundice.