The occurrence of "windswept deformity" in the legs of otherwise healthy African children in the second or third year of life is illustrated by three typical case histories. The usual causes of epiphysial abnormality were absent in these and other similar patients seen recently in central Nigeria. It is suggested that an unrecognised hereditary dysplasia of bone, possibly of local geographical distribution and associated with a phase of epiphysial instability due to rapid growth, might underlie the sudden onset of this striking deformity.