Some studies have suggested that bone turnover markers (BTM) and collagen type I alpha 1 gene (COLIA1) may be useful in the prediction of rates of future bone loss, and may therefore provide information about fracture risk. Our study aimed to examine the association of the COLIA1 genotype with the risk of vertebral fracture and to investigate the predictive value of this genetic factor in comparison with bone mineral density (BMD) and BTM, in ambulatory postmenopausal Spanish women. We determined the COLIA1 polymorphism by polymerase chain reaction, BMD by dual-energy X-ray absorptiometry and BTM in 43 postmenopausal women with prevalent vertebral fracture and a control group of 101 postmenopausal women without fracture. There was a significant overrepresentation of the 'T' allele in fractured women ( p = 0.029). BTM exhibited no differences between women with or without fractures or COLIA1 genotype groups. After adjusting for all other variables, the osteoporosis densitometric criteria variable was the most strongly associated with fracture (OR = 5 [1.8-13.3]) followed by COLIA1 (OR = 2.1 [1-4.3] per copy of the 'T' allele). Our study shows that COLIA1 is associated with prevalent vertebral fracture independently of bone mass, and the performance of this genetic factor to assess prevalent vertebral fracture is better than bone turnover markers.