Purpose: To evaluate the efficacy of prophylactic antibiotics for dental implant placement. Materials and methods: Twelve Italian private practices agreed to participate in this trial, each centre providing 30 patients. One hour prior to implant placement, patients were randomised, for consumption orally of 2 g amoxicillin or identical placebo tablets. Patients needing bone augmentation procedures were not included. Outcome measures were prosthesis and implant failures, adverse events and post-operative biological complications. Patients were seen 1 week, 2 weeks and 4 months post-operatively. Results: One centre did not deliver any data and 14 patients had to be excluded from the trial for various reasons. One hundred and fifty-eight patients were evaluated in each group and none dropped out at 4 months. Two prostheses and two implants failed in the antibiotics group, compared with four prostheses and nine implants in the placebo group. There were no statistically significant differences for prosthesis failures, implant losses, complications and side effects. Conclusions: No statistically significant differences were observed. However, four times more patients in the placebo group experienced implant failures than in the antibiotic group, and this requires further investigation. Schlagwörter: amoxicillin, antibiotic prophylaxis, dental implants, multicentre randomised placebo-controlled clinical trial