Diagnostic devices and methods are provided. The diagnostic devices preferably comprise a test strip with a test area. The sample to be analyzed contacts the test area, which comprises a specific binding partner for the analyte of interest. Analyte, if present in the sample, binds to the immobilized binding partner in the test area and is subsequently contacted with a conjugate. The conjugate specifically binds the analyte and provides a visual indication of the presence of the analyte. The devices may be used for the diagnosis of particular diseases or disorders in a patient, such as HIV or hepatitis. They may also be used to determine if an individual is pregnant.