OBJECTIVE To describe if weekly determined lung ultrasound (LU) scores in preterm infants born before 32 weeks (PTB32W) change with diuretic therapy. DESIGN This is a secondary analysis of a prospective study about weekly performed LU in PTB32W: we included infants who received diuretics, and compared LU scores according to their evolution on respiratory support (RS) before and after diuretics. RESULTS We included 17 PTB32W. Both groups were similar in terms of median gestational age: 26 weeks (interquartile rank (IQR) 25-28) in the responders group, and 27 weeks (IQR 25-29) in the other; but different in median number of days on invasive mechanical ventilation: 27 (IQR 11-43) vs. 76 (IQR 35-117) in the non-responders group, p=0.03; and number of infants with moderate-severe bronchopulmonary dysplasia: 2 (25%) vs. 8 (89%), p=0.005. The responders group showed lower LU scores at one week after diuretics: median LU score 3 (IQR 0-10) vs. 12 (IQR 12-12) in the non-responders group, p=0.04; and after three weeks of treatment: median value 6 (IQR 3-6) in the responders group vs. 12 (10-15) in the non-responders group, p=0.01. The decrease in RS was achieved since the beginning of diuretics: 4 out of 8 (50%) were extubated in the responders group, and 8 out of 9 (11%) in the non-responders group, p=0.048. CONCLUSIONS There is a group of PTB32W whose LU score improves after diuretics. This change appears later than that observed in the RS.