The total protein concentration and the protein profile were studied in 40 healthy premature newborn infants at the second day of life. The results were compared to those obtained for 40 full-term healthy newborn infants. Results pertinent to this last group were reported previously. Results here reported confirm that there is a higher total protein concentration in the cerebrospinal fluid of the premature newborn infant. Statistical analysis shows that the difference is significant (t : 2.16). The mean protein profile shows a protein fractions distribution proper to the "mixed profile type". The absence of tau-fraction was the most commonly finding observed in this way. Data were compared to those reported in the literature, and they were also considered proper to immaturity conditions of blood brain barrier.