The purpose of this study was to examine the effects of music on selected stress behaviors, weight, caloric and formula intake, and length of hospital stay. Subjects were 52 preterm and low birth weight newborns in a newborn intensive care unit (NBICU) who were in stable condition and restricted to isolettes. Subjects in the experimental and control groups were matched for equivalency based on sex, birth weight, and diagnostic criticality. Eleven males and 15 females were assigned to the control group and received routine auditory stimulation. The experimental group of 11 males and 15 females received music stimulation, which consisted of approximately 60 minutes of tape recorded vocal music, including lullabies and children's music, and routine auditory stimulation. Thirty-minute segments of the recording were played alternatively with 30 minutes of routine auditory stimulation three times daily. Exposure to music stimulation occurred only during the infants' stay in the NBICU. Results suggest music stimulation may have significantly reduced initial weight loss, increased daily average weight, increased formula and caloric intake, significantly reduced length of the NBICU and total hospital stays, and significantly reduced the daily group mean of stress behaviors for the experimental group. Data analyses suggest the length of hospital stay may be correlated with the amount of stress experienced by the neonate and not with weight gains. Theoretical and practical aspects of these results are discussed.