We describe four children with dysmorphic syndrome with severe learning disability (SLD). Their chromosomes had been normal on conventional cytogenetic examination. However, screening using a multiprobe fluorescence in situ hybridisation (FISH) technique for subtelomeric abnormalities revealed a deletion of the p arm of chromosome 1. The physical features include body asymmetry, microcephaly, distinctive facies with deep-set eyes, sharply defined eye sockets, and mid-face hypoplasia; the neurodevelopmental profile was characterised by SLD, motor delay with hypotonia, markedly delayed visual maturation, and postural asymmetry together with epilepsy. This phenotype is consistent with that described for partial monosomy for 1p36.3.