The current study examined the persistence and phenotypic presentation of inattention/overactivity (I/O) into early adolescence, in a sample of institution reared (IR) children adopted from Romania before the age of 43 months. Total sample comprised 144 IR and 21 non-IR Romanian adoptees, and a comparison group of 52 within-UK adoptees, assessed at ages 6 and 11 years. I/O was rated using Rutter Scales completed by parents and teachers. I/O continued to be strongly associated with institutional deprivation, with continuities between ages 6 and 11 outcomes. There were higher rates of deprivation-related I/O in boys than girls, and I/O was strongly associated with conduct problems, disinhibited attachment and executive function but not IQ more generally, independently of gender. Deprivation-related I/O shares many common features with ADHD, despite its different etiology and putative developmental mechanisms. I/O is a persistent domain of impairment following early institutional deprivation of 6 months or more, suggesting there may be a possible pathway to impairment through some form of neuro-developmental programming during critical periods of early development.