Cataracts may arise in association with various major and minor disorders restricting galactose metabolism, and the risk is broadly associated with the degree of galactose intolerance. A family is described in which a girl presented at the age of 7 3/4 years with cataracts, galactosuria, and partial deficiencies of the enzymes galactokinase and galactose-1-phosphate uridyl transferase. Galactose intolerance as determined by an oral test was impaired and fluctuated with variation in activity of the above galactose enzymes. Minor defects were also present in the parents and a maternal half-brother. The child has a compound disorder of galactose metabolism differing from those previously described. Assessment of galactose tolerance may be useful in the investigation of families with an incidence of cataract.