Introduction & Background: According to socioeconomic burden of neonatal jaundice, it is important to provide interventions that reduce the severity and duration of treatment. Given the ease of probiotics usage; the aim of this study was to determine the effect of probiotics on the level of bilirubin and during hospitalization due to physiological jaundice in term neonates. Methods: The present study was a randomized clinical trial study performed in Kamali Hospital, Alborz Province, Iran, which has the most equipped neonatal intensive care unit. The study samples were all neonates with 37-42 weeks gestational age hospitalized in neonatal intensive care unit and neonates with physiologic jaundice referred to the hospital up to 5 days after birth. Sampling was based on availability and randomized using a randomized number table. the intervention group received lactosacidophilus probiotic with milk two time per day in addition to phototherapy; And the control group was treated only with phototherapy. the bilirubin of both groups was checked daily and written in a table ; Finally, bilirubin level at admission and discharge time and also duration of hospital stay in both groups were compared using SPSS software. Results: There was no statistically significant difference between demographic characteristics in the control and Intervention groups. The results showed that there was no statistically significant difference between two group bilirubin level mean at discharge and hospitalization time (p=0.68). The Mann-Whitney test showed that the length of stay in the hospital was 0.7day shorter in the Intervention group and this difference was statistically significant (p=0.002). Conclusion: use of Lactobacillus bifidus Probiotic reduces hospital stay duration in neonates with physiological jaundice but has no effect on bilirubin level.