Purpose: At stage II surgery during dental implant treatment, early marginal bone loss around the implant occasionally occurs despite a lack of apparent causal events, and the etiology of this bone loss is unclear. This study was designed to investigate whether the bone morphogenetic protein-4 (BMP-4) genetic polymorphism is associated with early marginal bone loss around implants. Materials and Methods: The BMP-4 polymorphism was detected by restriction fragment length analysis using HphI digestion after polymerase chain reaction. A total of 262 implants were placed in 41 patients, and early marginal bone loss was observed in 25 of the 109 maxillary implants and 14 of the 153 mandibular implants. Results: In the mandible, the patients with the BMP-4 AV genotype had a significantly higher rate of occurrence of marginal bone loss than those with the BMP-4 VV genotype (P = .012). According to multiple logistic regression analyses, the odds ratio of the AV versus the VV BMP-4 genotype was 8.106 between patients with and those without bone loss in the mandible (95% CI = 1.30 to 50.51; P = .025). Discussion: These results suggest that the BMP-4 genetic polymorphism influences early marginal bone loss around implants. Conclusion: While perhaps premature in recommendation, genetic screening before implant surgery may prove to be a very useful aid to consider the risk of implant treatment.