Premature infants display few behaviors that provide quantitative information about their maturational development, making it difficult to carry out appropriate care. This study was performed to investigate the effect of non-nutritive sucking on behavioral state and physiological changes in premature infants. They were selected from premature unit of Main University Hospital at Tanta city. Forty premature infants were divided into two groups, nonnutritive sucking and no non-nutritive sucking. Personal characteristics were obtained from medical records. Anderson Behavioral State Scoring Systems were used and observed four times daily. Physiological changes were noticed; temperature, heart and respiratory rates The present study revealed that the time spent in sleep states was decreased and time spent in awake states was increased, when compared to no non-nutritive sucking group (ONNS). There was Statistically significant differences within the two groups related to behavior states and physiological changes. The development of sucking reflex was accelerated among premature in the non-nutritive sucking group. They shift earlier to oral feeding and their discharge was earlier.