Drug induced mania is sometimes associated with drug that are primarily not used for central nervous system effects. Here we report a manic episode during the treatment of leukemia with various agents in an adolescent with diagnosis of high functioning autism. In this case, most likely candidates to induce a manic episode were dexamethazone, a corticosteroid used in the treatment of T-ALL, cyclophosphamide and cotrimoxazole. Although literature on mood disorders associated with corticosteroids exceeds that of cyclophosphamide and cotrimoxazole, an absolute causal drug cannot be stated.