Anaplastic large cell lymphoma (ALCL) is a well-recognized subtype of non-Hodgkin lymphoma in childhood. Several series report experience with the diagnosis and management of pediatric ALCL, the average age at diagnosis being 8 to 16 years, with a reported range of 1 to 15 years. We present a case of ALCL affecting a 5-month-old infant in whom the diagnosis was confirmed by the nuclear and cytoplasmic immunohistochemical expression of ALK1, in addition to the presence of classical t(2;5)(p23;q35) translocation detected using reverse transcriptase-polymerase chain reaction. This is the youngest case of ALCL thus far reported and hence expands the spectrum of infantile lymphoproliferative disorders.