Ten cases of disintegrative disorder were identified within a larger sample of 165 individuals who met behavioral criteria for autism. These cases were compared to autistic individuals whose disorder had been recognized by age 2 and to those whose disorder had been recognized after age 2. Consistent with previous reports, children with disintegrative disorder had a period of normal development preceding the onset of a profound developmental regression from which they made, at best, only a limited recovery. Both clinical features at the time of regression and various outcome measures support the validity of the diagnostic concept, particularly when such cases are compared to "late onset" autistic ones.