Objective: We aimed to investigate the efficacy of ibuprofen doses in closing patent ductus arteriosus (PDA) and the possibility of reducing drug-related complications by reducing dose number.Methods: We performed a prospective study with 60 premature infants (33 weeks) who were treated with enteral ibuprofen for hsPDA. Echocardiographic examinations were performed before each dose. Treatment was stopped when PDA was closed and patients were followed for reopening and complications.Results: Rates of closure were 28.3%, 44.1%, 54.1%, 36.3%, 42.8% and 50.0% with the 1st, 2nd, 3rd, 4th, 5th and 6th doses. No closure was observed with 7th, 8th and 9th doses. Reopening was observed only in patients whose PDA closed with the 1st (3.3%), 2nd (1.6%) and 3rd (1.6%) doses. PDA diameters were higher in patients who required >4 doses. Complications were rare (6.6%) but unrelated with dose number.Conclusions: We conclude that it is possible to minimize ibuprofen exposure and achieve high closure rates of PDA in premature infants by performing echocardiography before each dose. PDA diameter should be used to estimate the duration of treatment. This approach is not effective in reducing complication rates and must be performed in attention to reopening especially for the first three doses.