Cryptosporidiosis has come to recent prominence as a cause of diarrhoea throughout the world in both adults and children, producing either an acute self-limiting diarrhoea or a protracted chronic diarrhoea which can be fatal in immunosuppressed patients. This study was therefore conducted to assess the prevalence of the infection among children less than five years of age in a rural community in Kiambu District, Kenya. 1420 diarrhoea specimens from children less than five years which were processed for bacteriology and parasitology were also examined for Cryptosporidium oocysts, using the modified Ziehl-Neelsen (ZN) acid-fast stain, 3.8% of all the diarrhoea samples were positive for oocysts. 320 non-diarrhoeic stools from children in the same age group were also examined and were all negative for Cryptosporidium oocysts. The results of this study would imply that infection with Cryptosporidium is associated with acute childhood diarrhoea in Kenya.