In an infant with galactosemia high levels of galactose-1-phosphate in red blood cells and of blood galactose were observed under a "galactose-free'' diet. The child did not thrive and developed a liver cirrhosis. At the age of 5 months he died unexpectedly. Post mortem examination revealed in the pancreas and the small intestine changes suggestive of a cystic fibrosis. Since the exogenous administration of galactose by diet could be excluded the endogenous production of significant amounts of galactose-1-phosphate has to be considered.