Purpose: The aim of this ongoing prospective study was to determine the 5-year survival rate of short porous implants in the posterior atrophic mandible. Materials and methods: In 40 partially edentulous patients, 55 short porous implants were placed. The implants used were of two lengths (5 and 7 mm) and two different diameters (4.1 and 5 mm) and were chosen according to the available crestal height and width. The unloaded healing period was 4 months. Twenty-one implants were restored with single crowns, 32 were splinted to the adjacent implant, 2 were used with an overdenture and were followed for 5 years. Outcome measures were prosthesis failures, implant failures and complications. Results: No patients dropped out. Nine implants were removed: 1 implant at uncovering and 8 after prosthetic loading. Eight patients lost 1 implant and 1 patient lost 2 implants. Four crowns failed. No complications occurred during the healing period. In 2 patients severe peri-implantitis occurred after loading and the implants had to be removed. At the end of the follow-up period the survival rate was 84% at implant level and 80% at patient level. Conclusions: The use of short porous implants showed an acceptable clinical outcome in the treatment of the posterior mandible in this interim 5-year report. These preliminary results must be confirmed by longer follow-ups. Keywords: implant prosthesis, posterior mandible, short dental implants