Three patients with features of the D syndrome were found to have 46 chromosomes and a pattern interpreted as representing a D/D translocation. It is of interest that these 3 patients and 3 patients from other centers were males in contrast to the predominance of females in the standard chromosomal D trisomy. These patients with translocation were born to young mothers, a fact which also contrasts with the increased age of mothers of infants with the standard form of D trisomy. One infant had an Arnold-Chiari malformation and a meningomyelocele, which have not previously been reported in this syndrome. Nuclear projections were identified in mature granulocytes from the third infant; they were studied by light and electron microscopy.