29 children with 32 duplicated thumbs were followed up. Wassel's classification was used: type I (3 cases), type II (8 cases), type IV (16 cases), type V (3 cases), type VII (2 cases). There were no type III or VI cases. Seven cases were not operated on (minor abnormalities, refusal by the parents). Simple surgical ablation was performed in 12 cases, ablation with reconstruction in 10 cases, ablation with pollicisation in one case, ablation with longitudinal osteotomy in one case. Finally, Bilhaut's technique was performed in one case. 16 cases had a good result, 9 cases were disappointing with one case of stiffness, one step deformity, one protrusion of the metacarpal head and particularly 6 cases with joint instability. This latter complication is the most frequently encountered in various series and the authors emphasize the surgical precautions to avoid its occurrence.