The interesting association between delayed presentation of right-sided diaphragmatic hernia and neonatal Group B streptococcal infections occurs rarely and its pathogenesis is still obscure. Two preterm newborn infants with early onset of neonatal sepsis (one due to Group B Streptococcus) followed by recognition of right-sided diaphragmatic hernia on the 9th and 25th day of life are reported. In both cases the course of neonatal sepsis and pneumonia was complicated due to the appearance of right-sided pleural effusion and atelectasis. On serial chest roentgenograms right-sided bowel gas was noticed and the liver shadow became gradually elevated. Diagnosis was confirmed by ultrasonography and computed tomography. Suspicion of associated diaphragmatic hernia should be raised in neonatal streptococcal infection whenever subsequent progressive respiratory deterioration ensues, requiring mechanical ventilation after initial clinical improvement or in the presence of right-sided pleural effusion.