Thirty-seven patients, 19 males and 18 females, with a mean age of 37.6 years (range 9-62), underwent atlantoaxial fusion for atlantoaxial instability associated with pseudarthrosis of the odontoid, fixed rotary subluxation, rheumatoid arthritis, and mongolism. Two operative techniques were used: transarticular C1-C2 screws and posterior bone grafts according to Magerl, but without posterior wiring, in 24 patients (group 1), and C1 lateral mass screws/C2 pedicle screws, plates and posterior bone grafts, according to Goel, in 13 patients (group 2). The mean follow-up period was 27.6 months. In both groups 92% of the patients were free of neck pain. In group 1, 4 out of 9 patients with neurological involvement improved one Frankel grade and in group 2, 3 out of 5. The fusion rates were 96% and 100%, respectively; they were superior to the rates mainly seen after a Gallie fusion: 67 to 86%. One vertebral artery injury without sequelae occurred in group 1, and one wound infection, that healed with debridement, in group 2. In conclusion, the results were excellent in both groups, but slightly better in group 2.