Gross skeletal and other malformations occurred in three older male siblings of two unrelated males with glucose-6-phosphate dehydrogenase-deficient erythrocytes. A history of maternal ingestion of promazine hydrochloride ¥.as obtained in one relevant pregnancy, of phenolphthalein in another, and of phenacetin, acetylsalicylic acid and extract of the pods of senna in the third. The possible significance of these observations is discussed.