The invention provides antibodies that specifically bind to OX40 (CD 134), referred to as OX40 antibodies, anti-OX40 or anti-OX40 antibodies. Invention antibodies that specifically bind to OX40 include mammalian (human, primate, etc.), humanized and chimeric anti-OX40 antibodies. Invention antibodies and antibody subsequences (fragments) that specifically bind to OX40 include purified and isolated antibodies, as well as pharmaceutical formulations thereof, are useful in various methods including treatment, screening and detection methods.本發明提供可專一結合OX40(CD134)之抗體,其稱為OX40抗體、抗-OX40及抗-OX40抗體。本發明可專一結合OX40之抗體包括哺乳動物(人類、靈長類等)、人類化及嵌合性抗-OX40抗體。本發明可專一結合OX40之抗體及抗體序列(片段),包括純化及分離之抗體,以及其醫藥調配物,可用於各種方法之中,包括治療、篩選及偵測方法。