In urban areas in Nouakchott, diarrheal diseases present a major public health problem, especially for children and adolescents. In August, 2008, a cross-sectional survey of 300 households in two adjacent districts of the city sought to study correlations between diarrheal disease and environmental health. The results show that 87 children of all ages had about 139 episodes of diarrhea, for an average prevalence of 14.8% that varied by age (23.6% in children younger than 5 years and 9.7% among children aged 5 to 14 years) and area (16.8% in Tevragh-Zeina and 28.3% in Sebkha). The univariate analysis indicates that 52% of the diarrhea risk was due to precarious basic hygiene. Studies of the specific causes of diarrheal diseases to help improve their treatment are necessary to supplement these epidemiological results.