Jejunal mucosa repair kinetics was studied in fed (control) and experimented Wistar rats refed after varied periods of starvation. According to the terminology (Le Maho et al., Am.J.Physiol. 1981,241,E342) denutrition reached phase PII after 5 days of starvation and reversible phase PIII after 8 days at least. Such a situation occurs spontaneously in the wild for some animals. During PII, 50% lipids stores are depleted whereas during PIII proteins stores are also depleted. Rats were refed ad libitum (standard pellet) for 1, 3, 7 days and until recovering of the initial body weight. Samples of jejunal mucosa were processed for morphometry and ultrastructural studies. Starvation induced a significant decrease of the total intestine mass (PII 35%, PIII 40%), of the proper mucosal lamina mass (PII 54%, PIII 60%), of the size of the jejunal villi (PII 37%, PIII 55%), and of the crypts (PII 15%NS, PIII 36%). As early as 16 hours after refeeding, villi and crypts size increased significantly to reach values, after 3 days of refeeding, not significantly different from control (villi: PII 88%, PIII 89%; crypts: PII, PIII 96%). At this time, intestine and mucosal masses were completely restored. However, structural homogeneity of the jejunal mucosa was not yet restored even after complete mass recovery.