The purpose of this study Is to assess the retained range of motion[RROM] of the foot after arthrodesis of the ankle joint, which might help designing the angle of arthrodesis. We reviewed the results including the RROM in 14 cases of ankle arthrodesis. Underlying causes included trauma group(six posttraumatic arthritis) and disease group(three osteoarthritis, three Charcot joints, one chronic synovitis and one pyogenic arthritis). We measured the RROM on the lateral roentgenograms of the ankle in full dorsiflexion and plantarflexion, The results were assessed by the AOFAS hindfoot scale[score]. The RROM in sagittal plane was $23.4{pm}5.3$ degrees and the score was 71.5 points on average. The RROM and the score were $26.8^{circ}{pm}2.1$, 81.2 points respectively in trauma group and $20.8^{circ}{pm}5.6$, 64.3 points in disease group; $26.6^{circ}{pm}2.3$, 83.4 points in cases younger than 40 years of age and $21.6^{circ}{pm}5.7$, 64.9 points in the older. The mean score was 77.3 points in cases whose RROM were $24^{circ}$ or more and 61 points in cases of less RROM; 69.6 and 73.4 points in cases with and without adjacent degenerative arthritis respectively. The score was 69.7, 73.3 and 71.5 points in cases whose angle of arthrodesis was in dorsiflexion, neutral, plantarflexion respectively. In conclusion, after ankle arthrodesis RROM of the foot was $23.4^{circ}$, and the more the RROM, the higher the score. In cases with sufficient amount of RROM, the angle of fusion on sagittal plane might not influence the result significantly.