Purpose: This study aims to verify the effect of hypercholeresterolaemia on implant and bone augmentation failures. Materials and methods: A retrospective cohort study was conducted on 268 sequential patients scheduled for implant and bone augmentation surgery under conscious sedation in a private practice. Total serum cholesterol (TC) levels were assessed via blood tests before surgery. Patients were divided into two groups: TC 200 mg/dl and TC > 200 mg/dl. A 6-month post-loading follow-up was scheduled both for implants and grafts. The outcomes considered were implant failure (removal) and graft infection/failure. The effect of cholesterol on early implant and grafting failure was investigated according to a logistic regression model. Results: Two hundred and twenty-seven patients fulfilled inclusion criteria; 139 had hypercholesterolemia. The 6-month post-loading overall implant failure rate was 6.25% at patient level (2.00% at implant level). Partial or total graft infection rate was 10.2%. High TC increased by 7.48 times the odds of the grafting failure (P = 0.047; 95% CI: -0.94 to 59.23), whilst it did not modify the odds of implant failure (P = 0.749; 95% CI: 0.28 to 2.49). Conclusions: High total serum cholesterol levels tend to increase graft failure rates whilst it did not influence implant failures. Keywords: bone augmentation, cohort study, dental implants, hypercholesterolaemia, implants failure, infection