AbstractGrowth data–stature, body weight, occipito‐frontal circumference (OFC), ear length and mean testicular volume (MTV)—in 61 males with the fragile X syndrome are presented. Small increases in the mean OFC and ear length and large increases in the MTV were found. The overgrowth of the head was evident in childhood. The characteristic facial appearance was deemed to be present in 60% of the subjects and was recognizable in childhood. Macro‐orchidism (MTV of ≥ 30 ml) was present in 80% of the adults but none of the children.Five subjects had a cleft palate, 11 serious eye disorders (3 with congenital nystagmus), and 4 had torticollis and/or kyphosis.Limited information on development suggested that mental retardation was present from early life and was not progressive. Although 3 subjects were autistic (2 with self abuse) most were pleasant, even tempered and cooperative men