ObjectiveTo examine the feasibility of a trial allocating different blood pressure (BP) intervention levels for treatment in extremely preterm infants.DesignThree-arm open randomised controlled trial performed between February 2013 and April 2015.SettingSingle tertiary level neonatal intensive care unit.PatientsInfants born InterventionsInfants were randomised to different levels of mean arterial BP at which they received cardiovascular support: active (Main outcome measureInotrope usage and achieved BP.ResultsOf 134 cases screened, 60 were enrolled, with mean gestation 25.8 weeks (SD 1.5) and birth weight 817 g (SD 190). Invasively measured BP on the first day and inotrope usage were highest in the active and lowest in the permissive arms. There were no differences in haemodynamic or EEG variables or in clinical complications. Predefined cranial ultrasound findings did not differ significantly; no infants in the active arm had parenchymal brain lesions.ConclusionThe BP threshold used to trigger treatment affects the achieved BP and inotrope usage, and it was possible to explore these effects using this study design.Trial registration numberISRCTN83507686.