Two anatomic reconstructions for correction of chronic lateral ankle joint instability were compared. In a prospective, randomized study, 60 patients were allocated to one of two treatment groups: reconstruction of the ligaments as described by Karlsson et al. (Group I) or with the modification of the Broström procedure as described by Gould et al. (Group II). The functional results were evaluated with a scoring scale, and the mechanical stability with standardized stress radiographs. The minimum follow-up period was 2 years. The functional results were satisfactory in 27 of 30 (90%) patients in Group I and 25 of 30 (83%) in Group II. There was no significant difference between the groups regarding mechanical stability. The mean anterior talar translation in Group I was 7.1 mm (range, 4 to 10) at followup, compared with 6.7 mm (range, 3 to 9) in Group II. The corresponding values for talar tilt were 4.9 degrees (range, 0 degree to 8 degrees) in Group I and 4.4 degrees (range, 0 degree to 8 degrees) in Group II. The duration of operation time was significantly longer in Group II and surgical complications were more frequent, probably due to the more extensive surgical exposure. This study showed that the majority of patients with chronic ankle instability can be successfully treated with anatomic reconstruction of the lateral ankle ligaments. Mechanical stability was restored with both methods.