Diarrhea is one of the most frequent diseases occur globally, including Indonesia, with mostly infected children under five years old. Sumba Barat Daya (SBD) is one of area in Nusa TenggaraTimur (NTT) with limited water sources, including Kodi and Kodi Utara subdistricts. Kodi has riverthat is accessible for the population, while Kodi Utara has no clean water sources. The purpose ofthis study was to know the trend and prevalence of diarrhea in 2013, and its relation with age andthe availability of water sources Kodi and Kodi Utara, SBD district. This study used cross sectionaldesign using secondary data taken from local health service of SBD. This study found that numberof diarrhea cases in 2013 in the two subdistricts were fluctuated, with the highest cases belongedto population less than five years old. Prevalence of diarrhea in Kodi Utara (1.76%) was higherthan in Kodi (1.68%). Analytical test using chi square showed that prevalence of diarrhea in the twosubdistricts was significantly related to age (p<0.05), but it was not significantly related to the area(p>0.05). In conclusion, prevalence of diarrhea in Kodi and Kodi Utara was related to age, howeverit was not related with availability of water sources.