Previous reports suggest that duplication of the distal part of 2p causes a distinct syndrome. Of the 20 published cases, all resulted from a parental translocation. We report here clinical and cytogenetic data on three patients with dup(2p) and few, if any, of the physical findings of the syndrome. Our data suggest that dup(2p) is associated with an extremely variable phenotype which may be quite mild in some cases. It is also possible that many of the nonspecific developmental anomalies thought to be part of the syndrome may be caused by the accompanying deletion.