There are published reports stating that some of the congenital metabolic diseases, such as lysinuric protein intolerance, multiple sulphatase deficiency, galactosemia, Gaucher disease, Pearson syndrome, and galactosialidosis, might lead to secondary hemophagocytic lymphohistiocytosis (HLH). However, to date, to our knowledge, the long-chain 3-hydroxyacyl-CoA dehydrogenase (LCHAD) deficiency has never been investigated among patients with HLH. Here, we report on a patient who was referred to our institution for a differential diagnosis of pancytopenia, liver failure, and rhabdomyolysis. The patient was diagnosed with HLH. Further investigation revealed an underlying diagnosis of the LCHAD deficiency. Our case was reported to contribute to the literature, as well as the HLH clinic, emphasizing the consideration of LCHAD deficiency, especially in 1 to 6 months' old infants with laboratory findings of hypoglycemia, metabolic acidosis, and elevated creatine kinase.