Kangaroo care for preterm infants has great benefits for the parents and for the parent-infant bonding process. A clinical observational study was conducted in which several physiological variables were collected, including among others transcutaneous oxygen pressure, heart rate, respiratory rate, occurrence of apneic attacks, breathing pattern (studied with power spectrum analysis), behavioral states and rectal temperature, during kangaroo care in small preterm infants. Kangaroo-care did not significantly affect any of these physiological variables comparing the period of 1 h before, 1 h during and 1 h after kangaroo care. We conclude that kangaroo care is a safe method, even for very small nonstabilized preterm infants.