The adoption into the UK of children who have been reared in severely deprived conditions provides an opportunity to study possible association between very early negative experiences and subsequent brain development. This cross‐sectional study was a pilot for a planned larger study quantifying the effects of early deprivation on later brain structure. We used magnetic resonance imaging (MRI) to measure the sizes of three key brain regions hypothesized to be sensitive to early adverse experiences. Our sample was a group of adoptee adolescents (N = 14) who had experienced severe early institutional deprivation in Romania and a group of non‐institutionalised controls (N = 11). The total grey and white matter volumes were significantly smaller in the institutionalised group compared with a group of non‐deprived, non‐adopted UK controls. After correcting for difference in brain volume, the institutionalised group had greater amygdala volumes, especially on the right, but no differences were observed in hippocampal volume or corpus callosum mid‐sagittal area. The left amygdala volume was also related to the time spent in institutions, with those experiencing longer periods of deprivation having a smaller left amygdala volume. These pilot findings highlight the need for future studies to confirm the sensitivity of the amygdala to early deprivation.