In patients with lipodystrophies a post binding defect in insulin action has been described involving phosphorylation of the beta subunit of the insulin receptor, suggesting the presence of a genetically determined defect in insulin action; the receptor gene has been mapped to the distal short arm of chromosome 19 close to the break-point of a specific chromosome translocation frequently found in pre-B Acute Lymphoblastic Leukemia (ALL). We report on a 13 years old female patient with partial lipodystrophy, acanthosis nigricans and insulin resistance who developed a pre-B ALL. Since lipodystrophy and pre-B ALL are rare disorders, a possible causal relationship between the two diseases is suggested possibly mediated by a mutation in the insulin receptor gene.