The plasma peptide component (PPC) from ten melanoma (Mel), breast cancer (BC) and healthy individuals was examined by a combination of RP-HPLC, surface enhanced laser desorption/ionization time-of-flight mass spectrometry (SELDI-TOF MS) and tandem mass spectrometry. A three peak pattern (2023, 2039, 2053.5 m/z) was primarily observed in melanoma. Two peaks (2236.1 and of 2356.3 m/z) were found only in BC samples. Fibrinogen alpha and inter-alpha-trypsin inhibitor heavy chain H4 fragments were absent in both tumor samples.