Background The treatment of femoral neck fracture with internal fixation (IF) is recommended in younger patients and has compared to arthroplasty the advantage of retaining the femoral head. A big problem with osteosynthesis is though failure. Finding predictors for fixation failure is still an ongoing process and osteoporosis has been suggested as a predictor. Aim To correlate bone mineral density (BMD) in regard to failure of IF in osteosynthesized femoral neck fractures. Material and method In a health technology assessment study from 2005-2006 at Odense University Hospital, Department of Orthopaedic Surgery and Traumatology, 177 patients with femoral neck fractures accepted DEXA –scanning of the hip and lumbar spine assessing BMD. Final follow-up were 01.08.2010 and 142 patients with IF comprised the final cohort. The cohort consisted of 106 females and 36 males with a mean (CI) age of 77,1 (75,3-78,9). Failure is defined as revision surgery or new fracture. Results 69 patients had a t-score (total hip) below -2,5 SD as defined for osteoporosis. At 1 year the overall (dislocated) failure rate was 34,3 % (44,2 %), at 2 years 45,1 % (59,4 %) and at end of follow-up 49,2 % (62,1 %). In the cox regression analysis the following factors for failure were significant: dislocated fracture, osteosynthesis placement and prior fracture. There were no association for total hip BMD, neck BMD, age, sex, quality of fracture reduction, walking disability, independent living, alcohol or smoking. A cox regression sub analysis of the undisplaced fractures showed significant result only for osteosynthesis placement. Conclusion There is no association between BMD and failure of internal fixation in osteosynthesized femoral neck fractures.