Thrombocytopenia is a condition in which platelet count below 150 x 109/L. Neonatal thrombocytopenia (NT) accounts up to 35% of all patients admitted to neonatal intensive care unit (NICU). The underlying cause of NT can often be predicted by the onset time of thrombocytopenia and course of disease. The purpose of this study was to determine the risk factors of thrombocytopenia in term infants undergoing treatment at Prof. Dr. I.G.N.G. Hospital. Method: An observational analytical study using case-control design was conducted in 50 term infants from March 2021 to October 2021 in Prof. Dr. I.G.N.G. Hospital Denpasar Bali. Result: Total 25 infants with thrombocytopenia in case group and 25 infants without thrombocytopenia in control group. Most of the infants were dominated by female gender (54%), mean gestational age was 38 (± 1) weeks, birth weight 2,940 (± 445) gram, cesarean section (56%). In addition, 48% of patients were vigorous babies. Early-onset neonatal sepsis (EOS) was 76% and late-onset neonatal sepsis (LOS) was 14%, most infants had neonatal pneumonia 58% and necrotizing enterocolitis (NEC) 48%. Mothers with preeclampsia were 26%. Multivariate analysis showed EOS was risk factor for NT (OR 4.69; 95% CI 0.9 – 22.0) and NEC (OR 4.17; 95% CI 1.2 – 14.4). Conclusion: Early onset neonatal sepsis (EOS) and necrotizing enterocolitis (NEC) are risk factors for thrombocytopenia in term infants.