OBJECTIVE To assess the clinical behavior of inactive caries lesion on the occlusal sites of permanent molars over 4-5 years and to estimate the risk for progression of caries-inactive sites compared with sound ones. METHODS Clinical examinations were conducted at baseline (n = 258) and after 4-5 years and included the recording of dental plaque and dental caries at the occlusal surfaces and the eruption stage of each permanent molar. RESULTS One hudred ninety-three schoolchildren were followed (response rate of 74.8%), totalizing 1152 teeth. Of the children, 30.6% (n = 59) presented at least one molar containing an active lesion, filling, or that had been extracted; according to the activity criterion, inactive lesions presented around a twofold increased risk for caries progression than sound surfaces (OR = 2.34 95%CI = 1.51-3.62). Thirteen percent (n = 25) of the children presented at least one molar progressing to dentine cavity, filling, or extraction; according to the severity criterion, inactive caries lesions presented a significantly higher risk for progression when compared with sound surfaces (OR = 2.69, 95% CI = 1.50-4.83). CONCLUSIONS The vast majority of lesions (85-90%) identified as inactive enamel caries at baseline did not progress over 4-5 years. Despite this fact, it was possible to detect an increased risk for caries progression in caries-inactive occlusal sites compared with the sound ones. CONCLUSIONS Considering the low progression rates, inactive caries lesions do not need a specific caries-controlling treatment and should be monitored longitudinally in the same manner as sound surfaces.