A sensitive and reliable method for the simultaneous determination of Am-241, Np-237, plutonium radioisotopes and Sr-90 in soil and sediment samples is described. Analysis involves leaching of the samples in conc. HNO3, followed by radiochemical separation and purification. The radiochemical procedure begins with separation of Am-241/Sr-90, plutonium radioisotopes and Np-237 by anion exchange chromatography. Am-241 and Sr-90 from the combined effluent are separated using TRU resin and Sr resin. Counting sources for alpha spectrometric measurements were prepared by the microcoprecipitation technique. Radiochemical yields were determined using Am-243, Np-239 and Pu-242 tracers. Strontium recovery was determined gravimetrically and Sr counting sources were analysed by liquid scintillation counting. The method was successfully tested by analysis of six reference materials and on two sediment samples with high activities of the selected radionuclides. The results were compared with reference and literature values.