We investigated the relationship between the degree of alveolarization and ultrasound-assessed lung aeration in a validated preterm rabbit model of experimental bronchopulmonary dysplasia (BPD). Lung ultrasound findings were heterogeneously abnormal and consisted of zones with interstitial, interstitial-alveolar or consolidated patterns. The median radial alveolar count was 10.1 [8.4–11.5], 7.8 [6.1–9] and 7.3 [1.8–10.1] in rabbits with interstitial, interstitial-alveolar or consolidated ultrasound pattern, respectively (overall p = 0.036). Alveolar count and lung ultrasound score were significantly correlated (ρ = − 0.044 (95%CI: − 1; − 0.143), p = 0.009; τ-b = − 0.362 (95%CI: − 0.6; − 0.1), p = 0.017).