This study investigated hypoplastic enamel defects in a well-defined sample of Romano–Britons from the 3rd to the 5th century AD and compared the findings with a modern British sample investigated by the same authors. All 178 excavated skulls with intact dentitions were examined for hypoplastic defects using the Federation Dentaire International (FDI) Developmental Defects of Enamel Index criteria. Histopathological and microradiographic sections were prepared of 5 teeth. Hypoplastic defects were found in the teeth of 37% of skulls, with 25% having 4 or more teeth affected. The teeth most frequently involved were canines. Of the defects, 75% were horizontal grooves, 12.7% were pitting, and 7.1% were areas of missing enamel. The location of defects was 82% buccal, 16.5% lingual, and 1.2% occlusal. The reproducibility of diagnosis was 84%. Microscopic and microradiographic investigations showed areas of hypomineralization of enamel and wide zones of interglobular dentine related to the hypoplastic grooves. There was higher frequency, different morphology, and greater severity of hypoplastic enamel defects compared with the modern British sample. The defects may be related to repeated environmental stresses between the ages of 2 and 6 yr. Identified environmental stresses in these Romano–Britons, including high lead ingestion, poor nutrition, and recurrent infections, may be important etiological factors for the enamel defects.