Aims: The aim of this research was to examine the effect of thermal treatments on the viability and infectivity of Cryptosporidium parvum oocysts attached to a beef surface. Methods and Results: This study examined the effects of heat treatment ( 60 or 75 degreesC) on the viability of C. parvum oocysts inoculated onto the surface of beef muscle estimated by vital dye assay. The infectivity of the oocysts was assessed against monolayers of HCT- 8 cells. At 60degreesC viability of the oocysts decreased from 100% at T-0 to 64(.)2% at T-60. At 75degreesC the viability of the oocysts decreased from 100% at T-0 to 53(.)7% at T-15 and finally to 11(.)2% at T-60. Oocysts were rendered noninfective against monolayers of HCT- 8 cells following treatments of 60degreesC/45s and 75degreesC/ 20s. Conclusion: The washing of carcasses with hot water and standard thermal treatments is sufficient to kill C. parvum on beef. Significance and Impact of the Study: This study found that relatively mild heat, currently used to decontaminate and heat treat beef carcasses and to cook meat products, is capable of inactivating C. parvum.