This research investigated a novel procedure using microsatellite-telomere primers with PCR and PAGE to differentiate Cryptosporidium isolated from samples of three separate human groups in Australia and England, and to domestic sheep and cattle, to feral goats, and to kangaroo populations in three regions of Australia. Typing results have shown that the procedure can distinguish both common-origin and diverse origin types in groups of common contact humans ranging from 10 to 20 individuals. Both common and diverse types have been found in domestic sheep, feral goats, and kangaroos sharing the same grazing area. A single stable type has been found among representatives of all infected calves of a large dairy over a period of 3-years. Diverse types have been found among dairy calves at three different dairies within a 50-mile radius in one area of southeastern Australia. In summary, application of this procedure has revealed significant diversity among C. parvum samples isolated from naturally infected hosts in both human and animal populations. The findings suggest that general application of the procedure will provide for sensitive source tracking and molecular epidemiological investigation. Includes 5 references, table, figures.