The human heart-type fatty acid binding protein (H-FABP) can be used as an early heart infarction marker in clinical diagnostics because its concentration in blood plasma increases about 1.5 to 3 hours after the onset of an acute myocardial infarction. Hence, it is of main interest to determine an infarct with a fast immunosensor. Surface plasmon resonance spectroscopy (SPRS) is one of the most versatile and sensitive direct optical technologies used for biochemical sensors. The aim of this study is the development of a direct optical immunosensor for the detection of H-FABP. Two different SPRS devices have been constructed: the well-known planar configuration and a new promising fiber-optical transducer. Both transducers are compared under the same conditions with regard to the measurement of H-FABP. They show a similar response and an excellent correspondence of the calibration curves. The detection limit of H-FABP in a competitive assay is about 200 ng ml−1 in both cases.