The aim of the present study was to assess the effect of childhood malnutrition on salivary flow rate and pH. Four hundred children between 3-12 years were selected for this study. The children were divided into two main groups according to their nutrition status, Group (A): two hundred children representing the malnourished children, Group (B): two hundred children representing the control group. Within Group (A) Children were further divided into 2 subgroups, subgroup (1): one hundred stunted children and subgroup (2): one hundred underweight children. Every child was subjected to unstimulated and stimulated saliva flow and pH measurements and caries status evaluation using dmf index for primary and DMF index for permanent teeth. The results showed undernutrition (underweight) and stunting reduced the secretion rate of stimulated saliva and no effect on unstimulated salivary flow rate or saliva pH. Moreover, undernutrition
(underweight) increased the caries index of primary teeth, while stunting increased the caries index of permanent teeth. It was concluded that malnutrition causes enamel hypoplasia, salivary gland hypofunction and saliva compositional changes and these might be the mechanisms through which malnutrition associated with caries.