Lysosomal acid lipase (LAL) deficiency is a rare autosomal recessive disorder which causes two distinct clinical phenotypes: Wolman's disease and cholesterol ester storage disease. LAL hydrolyses LDL-derived triglycerides and cholesterol esters to glycerol or cholesterol and free fatty acids. Its deficiency leads to accumulation of intracellular triglycerides and/or cholesterol esters. In early onset LAL deficiency, clinical manifestations start in the first few weeks of life with persistent vomiting, failure to thrive, hepatosplenomegaly, liver dysfunction and hepatic failure. Adrenal calcification is a striking feature but is present in only about 50% of cases. We report a case of an infant presenting with vomiting, diarrhoea, hepatosplenomegaly and poor weight gain that was subsequently diagnosed as Wolman's disease. He was entered into a clinical trial for LAL replacement therapy. This case reinforces that early onset LAL deficiency should be considered in a baby presenting with failure to thrive, gastrointestinal symptoms and hepatosplenomegaly., (2014 BMJ Publishing Group Ltd.)