Purpose: The aim of this prospective study was to establish if ultrashort implants are a reliable therapeutic solution by evaluating their effect on mean crestal bone loss and assessing their survival and success rates. Materials and Methods: Patients were treated using 6-, 9-, and 11-mm-long implants with sandblasted and acid-etched surfaces and fitted with fixed partial prostheses. Clinical and radiographic examinations were scheduled yearly. Data collected included the implant positioning site, implant length and diameter, peri-implant bone loss (PBL), and clinical and anatomical C/I ratios. Results: One hundred eleven implants (6-mm-long, 30.6%) were positioned; two implants were lost before loading. During the 36-month followup, no other implants were lost (98.2% survival rate, 100% from loading), but four implants did not meet the criteria for success, due to excessive crestal bone loss, resulting in a 94.6% success rate, 96.3% from loading. Success rates and peri-implant bone loss were not significantly different among implants with different lengths. No correlation was observed between implant length and bone resorption. Conclusion: Six-millimeter-long implants did not show different results in comparison with 9- and 11-mm-long implants. They can be considered a reliable solution for implant prosthetic rehabilitation and a dependable and minimally invasive therapeutic option in areas showing severe bone resorption. Palabras clave: crown-implant ratio, implant length, implant success rate, prospective study, ultrashort implants