Anterior approaches to the lumbar spine are rapidly gaining popularity for decompressive and reconstructive procedures. A recognized hazard to this approach to the spine is possible injury to the great vessels. This retrospective study is a review of 102 consecutive anterior lumbar spinal procedures. All approaches were performed by one of two fellowship-trained vascular surgeons. Both have extensive experience with this approach. All injuries to the inferior vena cava, common iliac vein, or other great vessels that required suture repair were recorded. The authors were surprised to note an overall rate for this vascular complication of 15.6%. These injuries included 11 tears of the common iliac vein, four tears of the inferior vena cava, and one avulsion of the iliolumbar vein. Two different approaches were used during this study. Twenty-six cases were performed through a flank incision, with the dissection proceeding through the external and internal oblique muscles as well as the transversus abdominis. The average number of levels exposed was 2.3. Two vascular complications resulted, for an incidence of 7.7%. Seventy-six procedures were carried out through a small (5-10 cm) incision overlying the rectus abdominis muscle. The retroperitoneal space was entered through the posterior rectus sheath without division of any muscle tissue. This resulted in 14 vascular complications, for an incidence of 18.4%. Although the authors are unaware of any major long-term morbidity from this complication in their patient group, they believe feel that the true incidence of this potentially quite serious complication may be underestimated.(ABSTRACT TRUNCATED AT 250 WORDS)