We searched randomized controlled trials, meta-analysis and systematic reviews from OVID-EBM Reviews which included ACP Journal Club, The Cochrane Library, and MEDLINE（1991 to 2005 ） to evaluate clinical effectiveness of pit and fissure sealants for caries. The resultsshowed that pit and fissure sealants were recommended to prevent caries of the occlusal surface. The effectiveness varied between the two types of sealants, in general, flowable resin composite had a more satisfactory retention than glass ionomer composite. Acid etch was helpful for less microleakage and more satisfactory retention. Mechanical air-abrasion with acid etch may have the best border seal, However, we were not sure of the effectiveness of Er：YAG laser, technique of dental drill preparation and splicing. More high quality clinical trials on pit and fissure sealants are still needed.