The adsorption of organic molecules from solutions onto asbestos fibers was investigated by means of the computer-aided analysis of the electron paramagnetic resonance (EPR) spectra of neutral and charged nitroxides, in the absence and in the presence of a hydrophobic chain attached to the nitroxide group. Four different asbestos fibers were used for the present study, namely, chrysotile, belonging to the serpentine group, and anthophyllite, amosite, and crocidolite, belonging to the amphibole group. Neutral or negatively charged molecules, namely, the "chain-free" nitroxides 4-hydroxy-Tempo and Tempyo(-), were scarcely (<10%) adsorbed by the positively charged chrysotile surface, whereas the positively charged nitroxide CAT1 was better adsorbed (similar to 25%) by the negatively charged anthophyllite fibers. The radicals interacting with the asbestos surface showed a decrease in mobility. The adsorption was strongly enhanced in the presence of the hydrophobic chain attached to the nitroxide group that led to the formation of surface aggregates. The doxylstearic acids were preferentially adsorbed by chrysotile (similar to 80%). The adsorption increased with the increase in solvent polarity and in the chain length between the carboxylic and the doxyl groups. The positively charged surfactants CAT10 and CAT16 were adsorbed mainly by anthophyllite fibers. The packing of CAT16 aggregates was lower at the asbestos surface with respect to the micellar solution. In any case, amosite fibers showed poor adsorption ability, whereas the EPR spectra from crocidolite samples were at the limit of detectability, due to the spin-spin interactions between the adsorbed radicals and the paramagnetic metal ions at the surface. The vicinity of the interacting sites at the surface favored a high local concentration of the radicals adsorbed by chrysotile fibers, whereas low-packed surface aggregates were formed at the anthophyllite surface, due to the rather large separation among the interacting sites.