An IL-1.beta. binding antibody or IL-1.beta. binding fragment thereof comprising the amino acid sequence of SEQ ID NO: 2, and related nucleic acids, vectors, cells, and compositions, as well as method of using same to treat or prevent a disease, and a method of preparing an affinity matured IL-1.beta. binding polypeptide. IL-1.beta. binding antibodies or IL-1.beta. binding fragments thereof are provided which have desirable affinity and potency.