The isolation and biochemical/enzymatic characterization of an L-amino acid oxidase, Balt-LAAO-I, from Bothrops alternatus snake venom, is described. Balt-LAAO-I is an acidic glycoprotein, pI approximately 5.37, homodimeric, Mr approximately 123,000, whose N-terminal sequence is ADVRNPLE EFRETDYEVL. It displays a high specificity toward hydrophobic and basic amino acids, while deglycosylation does not alter its enzymatic activity. Balt-LAAO-I induces platelet aggregation and shows bactericidal activity against Escherichia coli and Staphylococcus aureus. In addition, this enzyme is slightly hemorrhagic and induces edema in the mouse paw. Balt-LAAO-I is a multifunctional enzyme with promising relevant biotechnological and medical applications.