Early loss of pit and fissure sealants is considered to be primarily dependent on inadequate isolation of the tooth from salivary contamination during application. Gradual additional loss is considered to be caused by occlusal wear, shearing forces, and marginal failure. Our hypothesis is that the caries risk of the child may be an additional factor in sealant loss. The objective of this study was to analyze the influence of caries history in primary teeth (dft index) on the success of sealants. Delton light-polymerized sealant was applied in 104 six- to eight-year-old children, followed for four years on a six-month-visit basis. All sound permanent first molars were sealed during the study. A survival analysis was used to describe sealant success over time. A Cox proportional hazards regression model was built to test the influence on sealant success of the dft index and site of sealant application (mandibular occlusal surface, maxillary fossae, and maxillary distolingual fissure), controlling for some potential confounders. Sealant half-life was 46 months. Site and dft index were related to sealant survival. The maxillary fossae showed the best retention, followed by the mandibular occlusal site and the maxillary disto-lingual fissure. The higher the dft, the higher the risk of sealant failure. This study has implications for sealant study designs and public sealant programs.