Fecal specimens from 200 stray dogs impounded at the San Bernardino City and County animal shelters were screened for Cryptosporidium sp oocysts, using the auramine-rhodamine fluorescent staining procedure. The University of California, Los Angeles acid-fast stain was used for confirmation. Only 4 (2%) dogs were passing cryptosporidial oocysts. Likewise, stool specimens from 664 people were submitted to the San Bernardino County Department of Public Health Laboratory for routine parasitologic examination and were screened for Cryptosporidium sp. Cryptosporidial oocysts were detected in 20 human fecal specimens (3.01%). On the basis of these findings, it appears that the human and canine populations of San Bernardino County are at low risk for development of cryptosporidiosis at this time.