Disclosed herein are isolated human monoclonal antibodies that specifically bind human mesothelin with a binding affinity of about 25 nM or less. Nucleic acids encoding these antibodies, expression vectors including these nucleic acid molecules, and isolated host cells that express the nucleic acid molecules are also disclosed. The antibodies can be used to detect human mesothelin in a sample. Methods of diagnosing cancer, or confirming a diagnosis of cancer, are disclosed herein that utilize these antibodies. Methods of treating a subject with cancer are also disclosed.