OBJECTIVE To investigate the clinical implications of two categories of fetal bilateral cleft lip and palate (BCLP): with premaxillary protrusion and with a flattened profile. METHODS This was a retrospective study of fetuses with a prenatal diagnosis of BCLP at the Department of Obstetrics and Gynecology of the University of Bologna in the period 1991-2005. RESULTS BCLP was diagnosed prenatally in 14 cases (mean gestational age at diagnosis, 21 (range, 12-36) weeks). In nine of these, there was a premaxillary pseudomass; in the remaining five, the profile was flat. Associated structural and/or chromosomal anomalies were found in two of the nine with a premaxillary pseudomass and in all five of those with a flat profile (P = 0.02). All fetuses with a flat profile had aneuploidies (three trisomy 18, one trisomy 13, one trisomy 8 mosaic), as did one of the nine with a premaxillary pseudomass. Eight of the pregnancies were terminated, including three of those with a premaxillary pseudomass and all five of those without. All continuing pregnancies resulted in live births, although one neonate affected by Krabbe's disease died shortly after birth. CONCLUSIONS Our findings suggest that a third of cases of BCLP diagnosed in utero have a flat profile and these are at high risk of lethal aneuploidies.