Qualitative and quantitative mass spectrometric studies of biomolecules for example proteins, peptides, or lipids contained in biological samples like physiologic fluids are very important for many fields of science such as medicine, veterinary medicine, biology, biochemistry, molecular biology, or environmental sciences. In the last two decades, MALDI TOF MS - matrix-assisted laser desorption mass spectrometry, proved to be an especially convenient tool for these analyses. The main advantages of this method are its rapidity and high sensitivity which is particularly appreciated in the case of studies of complex biological specimen. A major challenge for many researchers is to maximize this sensitivity, among others, by appropriate procedures of sample preparation for the measurement. The objective of this work was to optimize these procedures, selecting the optimal matrix and optimum proportions of the sample and the matrix solution in a mixture of both solutions, aiming at the achievement of the maximum intensity of ion current. In this respect, five low molecular mass cathelicidins were studied: prophenin-2, protegrins 1-3, PR-39. All of them were obtained directly from the porcine blood. As a result of studies, the authors determined such experimental conditions when the intensity of investigated ionic current had the highest value.