['Improved survival of very low birth weight (VLBW) premature infants requires urgent intensive care, professional nursing and medical care. On the other hand, long hospital stay period imposes emotional and economic burdens on the family and society. Therefore, it is necessary to clarify the most important factors affecting their hospitalization duration to lessen unwanted outcomes of premature birth and to eliminate or relieve the problems.', 'In a descriptive-analytical study, 170 low birth weight premature infants were assessed in a regular daily follow-up in Alzahra Hospital, Tabriz, Iran. Probable factors affecting NICU (neonatal intensive care unit) stay, such as birth age and weight, time of trophic feeding initiation, time of regain birth weight, and duration of parenteral nutrition, were evaluated. Data was analyzed using descriptive statistics and linier regression model in SPSS14. Statistical significance was considered at 0.05.', 'Mean birth weight and age of infants were 1310.26 ± 804.26 g and 30.51 ± 0.34 weeks, respectively. Duration of NICU stay was 14.51 ± 10.12 days. Intrauterine growth retardation, positive C-reactive protein (CRP) and blood culture during hospitalization stay, bloody or bile stained gastric remnants, days to regain birth weight, and total enteral nutrition intolerance were the most important factors affecting NICU stay among the studied infants.'] Do factors affecting the neonatal intensive care unit stay duration in very low birth weight premature infants?