A prospective study was conducted on 13 consecutive patients who received immediately loaded mandibular fixed-implant prostheses. The exclusion criteria were 1) general: heavy smoking, demonstrated bruxism, or general ill health and 2) local: lesions in the bone area to be implanted or inadequate morphology requiring augmentation techniques. After suturing the surgical wounds, impressions were taken, and transitional prostheses were screwed in within 2 weeks of surgery. A total of 61 implants of four different designs were placed. Thirty-two of the implants were placed at the same time as performing the extractions of the residual dentition. In 13 of the implants, there was a 2-month period between extraction surgery and implantation. The other 16 implants were inserted in alveolar bone that had been edentulous for more than 12 months. Despite these differences, all 61 implants were immediately loaded. Parallel x-rays were taken of the 13 patients at the time of transitional prosthesis placement, at the time of definite prosthesis placement, and 6 months later at the first control. During the 18-month follow-up period, two implants failed, and the remaining 59 implants were found to be clinically immobile, asymptomatic, and free of any radiolucency, giving a survival rate of 96.7%. Analysis of radiographic bone levels gives us a cumulative success rate of 93.4%. These figures are comparable to those obtained in similar studies and are no different than those from implant prostheses loaded in the conventional delayed manner. Based on these preliminary results, we can conclude that the immediate loading of mandibular implants is a viable and efficient approach.