Background: Nowadays, administering noninvasive positive airway pressure (PAP) is considered as the building block for the management of respiratory distress syndrome (RDS). Since nasal continuous PAP (n-CPAP) established its roots as an interventional approach to treat RDS, there have always been concerns related to the increased work of breathing in newborns treated with this intervention. Therefore, respiratory support systems such as nasal bi-level PAP (N-BiPAP) and sigh-PAP (SiPAP) have been developed during the last decade. In this study, two respiratory support systems which, unlike n-CPAP, are categorized as cycled noninvasive ventilation, are studied. Methods: This study was a randomized clinical trial done on 74 newborns weighing 1500 g or less affiliated with RDS hospitalized in NICU at Al-Zahra Hospital from October 2012 to March 2014. Patients were randomly assigned to two respiratory support groups of N-BiPAP and SiPAP. Each group contained 37 newborns who were compared, according to their demographic characteristics, duration of noninvasive ventilation, the need to administer surfactant, apnea incidence, the need for mechanical ventilation, pneumothorax, intraventricular hemorrhage (IVH), patent ductus arteriosus (PDA), the duration of oxygen supplement administration, and chronic lung disease (CLD). Results: The average duration of noninvasive respiratory support, and the average duration of the need for oxygen supplement had no significant difference between the groups. Moreover, apnea incidence, the need for mechanical ventilation, pneumothorax, IVH, PDA, CLD, the need for the second dose of surfactant, and the death rate showed no significant difference in two groups. Conclusions: In this study, SiPAP showed no significant clinical preference over N-BiPAP in the treatment of the newborns with RDS weighing <1500 g.