Abstract Objectives: to evaluate the effect of oropharyngeal colostrum immunotherapy on the length of hospital stay in preterm newborns with very low birth weight. Methods: interventional ambispective study, which consisted of eight daily administrations of 0.2 ml (four drops) of colostrum, totaling up to 56 syringes (for up to seven days). The control was historic. The main independent variable: length of hospital stay (days). Survival analysis was performed using the Kaplan-Meier Method and the survival effect was estimated - Log Rank Test (Mantel-Cox) and Breslow Test (Generalized Wilcoxon). A significance level of 5% was adopted. Results: of the 109 mother/child pairs, 56 were part of the treatment and 53 were part of the control group. There was no association between oropharyngeal colostrum immunotherapy and length of stay for preterm newborns with very low birth weight in the general sample. However, after stratification, a shorter hospital stay (42 versus 51 days, HR= 1.78, CI95%=1.02-3.09, p=0.04) was demonstrated among premature infants with ≥28 gestational weeks undergoing oropharyngeal colostrum immunotherapy. Conclusions: we found an association between oropharyngeal colostrum immunotherapy and shorter median length of hospital stay in the subgroup of premature infants ≥ 28 weeks of gestational age, but we did not find significant differences in those <28 weeks.