New and elaborate techniques for alpha-particle autoradiography of thick specimens based on the plastic nuclear track detector CR-39 have been developed. These permit a full analysis of both trace element and microdistribution of alpha-active nuclides present. The important features of the techniques are: 1. (1) reliable low level counting down to 10 −15Ci g −1, 2. (2) high resolution alpha-particle spectroscopy in CR-39, 3. (3) determination of the absolute abundance of alpha active nuclides present in the specimen, 4. (4) determination of the distribution of emission with height up to 30 microns above the surface of the autoradiograph, 5. (5) the local determination of the radon diffusion coefficient in the specimen which is needed to calculate the activity levels of 222Rn and daughter nuclei, 6. (6) the analysis of small and large clusters of alpha-particle activity recorded on the autoradiograph. These techniques are briefly discussed.