A family with "ant-egg" cataract in three generations is described. The cataract is congenital, probably of autosomal dominant inheritance. Light microscopy of the ant-eggs showed that they are made up of a peripheral zone of lens material and a large almost homogenous centre. Element analysis by X-ray spectrophotometry showed a high content of calcium and phosphorus in the centre. The cataract has been easy to operate on and the postoperative visual results have been good.