The present study compares the clinical presentation and diagnostic features of meconium ileus (MI) in newborns with and without cystic fibrosis (CF). A retrospective study of 43 patients treated in the Pediatric Surgical Center of Amsterdam was performed. Twenty-three of the patients (53.5%) were diagnosed as having CF. Complex MI was significantly more frequent in patients without CF, and these patients had lower gestational ages and birth weights than patients with CF. All of the patients with complex MI had homozygous DF508 mutations, whereas the patients with simple MI also had other mutations. None of the patients with other mutations had complex MI. Therefore, we conclude that the clinical entity of MI represents a spectrum of underlying pathologies.