BackgroundDiarrheal illness remains one of the most common causes of death among children specifically those who live in developing countries. Appropriate mothers' knowledge and practice regarding acute diarrhea illness in children can considerably reduce diarrhea-related morbidity and mortality. So, the aim of this study was to evaluate mothers' knowledge and practice regarding acute diarrheal illness in children. MethodThis cross-sectional study was conducted in a tertiary hospital in Riyadh, Saudi Arabia using a newly developed questionnaire that was distributed to King Abdullah Specialist Children. The calculated sample size was 375. ResultsA total of 375 mothers were included in this study and the majority of them (99%) were Saudis. More than half of the participants (61%) were university graduates. The majority (96.5%) chose previous experience as the main source of information about diarrhea while (40%) chose physician. Most of the mothers (69.6%) believed that teething is the leading cause of diarrheal illness in children. Regarding the treatment, fluid was recognized to be the major treatment for diarrhea as chosen by the mothers. Around (42.7%) of the respondents thought intravenous fluid is more effective than oral rehydration solution (ORS) in treating dehydration associated with diarrheal episodes. ORS was the main type of fluid (74.1%) which was selected by the mothers to be given during the diarrheal episode. ConclusionMothers showed good knowledge and practice overall in regard to acute diarrheal illness in children. However, this study revealed some misconceptions among the caregivers which necessitates more educational sessions to be conducted in the community and during the hospital visit.