Glass ionomer cement (GIC) has been widely used for Class II restorations in primary teeth, but there were few studies reported the long-term clinical performance of these restorations. Objective: The aim of this study was to evaluate systemically the clinical success rate of class II GIC restorations in primary molars as compared with Amalgam restorations. Methods: We searched the database from MEDLINE (Pubmed January 1960 to November 2003), limiting to only English language. Studies were randomized controlled trials comparing GIC restorations with Amalgam restorations in primary molars with at least 2 years of follow-up. Two reviewers independently assessed trial quality and extracted data. Primary and secondary lists of systematic criteria for use in the assessment of the papers were drawn up. Results: Ten publications were screened as being potentially relevant to the review, only three trials were found to meet the review's inclusion criteria. The success rate of GIC restorations ranged from 40% to 89.1%, and that of the Amalgam restorations from 91.3% to 100%. Conclusions: This review suggests that GIC are less favorable than Amalgam for restoring approximal caries in primary molars after a follow-up of more than 2 years.