Mass lesions were observed on the tricuspid valve by cross-sectional echocardiography in 5 neonates, 4 of whom presented with fetal distress. Four went on to develop severe respiratory distress, 3 from meconium aspiration and 1 from hyaline membrane disease, with 2 deaths despite intensive treatment. Autopsy confirmed meconium aspiration pneumonia. Sterile, unorganised vegetations were seen on the tricuspid valve (and in 1 infant the mitral valve too). Perinatal factors such as hypoxia, haemodynamic and coagulation disturbances may have contributed to the formation of the vegetations and may reflect the severity and refractoriness of persistent pulmonary hypertension.