The aim of this study was to attempt to determine the minimum effective regimen of amoxicillin antibiotic prophylaxis for dental implant surgery. One hundred patients were randomly allocated to 4 different antibiotic prophylactic treatment groups. At second-stage surgery, only 2 implants failed in the nonantibiotic group. No statistically significant differences were found in the 4 groups, probably because of the limited number of the samples. Until a study with a larger population may definitely rule on the role of antibiotics in oral implant surgery, in may be prudent for the practitioner to adopt the single preoperative antibiotic dose as the minimal effective regimen.