The detection of biological markers is critical not only for the early diagnosis of cancer but also for adjustments in antitumor therapy. Rapid, sensitive, and selective detection and monitoring of the content of specific biomarkers in real time are key to point-of-care testing diagnostics. We report the detection of heat shock proteins by fluorescence immunoassay with the appropriate phage antibodies, with a minimum detection limit of 1 ng/mL. The fluorescence immunoassay data were confirmed by dot immunoassay and by circular dichroism studies. The results of the study may help in the adaptation of the fluorescence immunoassay to cancer diagnostics.