Alcoholics have frequent bronchial and intestinal bacterial-associated infections compromising the mucosal-associated lymphoid tissues. Alcoholics also suffer undernutrition due to changes in their lifestyles. Thus, we studied the intestinal mucosa-associated lymphoid tissues using two types of diets in young and mature mice. The objective was to elucidate if ethanol consumption alters the T and B cell populations in the intestine, and if the alteration could be associated with the age and/or the nutritional status of the host. There was an increase in the number of CD8+ cells per field in the intestinal lamina propria (ILP) of young mice consuming ethanol, with no change in CD4+ and IgA+ cells in the ILP and CD4+ and CD8+ cells in the intestinal intraepithelium (IE). There was also an increase in the number of CD4+ and CD8+ cells in the ILP of well-nourished mature mice consuming ethanol, and an increase in the number of CD4+ cells in the ILP of undernourished mice. An increase in the number of CD8+ cells in the IE was also detected in the well-nourished group consuming ethanol. Therefore, we conclude that ethanol administration alters the intestinal mucosa-associated lymphoid tissue.