ABSTRACT Purpose To evaluate the oxygen saturation, heart rate, length of hospital stay and weight preterm infants or preterm newborns (PTNBs) (in the Neonatal Intensive Care Unit in the diet supply by cup and finger feeding techniques, simultaneously with breastfeeding. Methods Simultaneous randomized clinical trial. Twenty-five preterm infants admitted to the Neonatal Intensive Care Unit of the Public Hospital from October 2011 to February 2012 were selected. The sample was divided into two groups: Eight preterm infants who received the diet in the cup probe group (CPG) who were born on the same day, and 17 by finger probe group (FPG) who were born on the odd day. In the diet offer, the minimum and maximum values of oxygen saturation (O2 Sat) and heart rate (HR) were recorded: before offering the diet, during and after the offer. Results Regarding the variables O2 Sat and HR, no statistically significant differences were observed between the groups, but in the group vs time factor, the groups showed differences, not continuous in the O2 Sat variable. Regarding weight, a statistically significant gain was observed for both groups, and in CPG the highest weight gain was due to the longer hospitalization time. It was verified that FPG presented shorter hospitalization time. Conclusion There were no differences regarding O2 Sat and HR. However, when analyzing the time factor, the groups presented some differences, not continuous, indicating the need for other studies for a better understanding of the effect. The FPG presented shorter hospitalization time and the CPG infants had greater weight gain due to longer hospitalization time.