The purpose of this study was to assess the effect of 18-week Tai Chi training on body balance in dynamic trial among elderly men. The study covered 49 subjects from age 60 to 82.1 years, who had osteopenia or osteoporosis. The subjects were recruited from the community by direct mailings and community efforts to participate in studies. The participants were randomly assigned to either the exercise intervention (n = 25) or control groups (n = 24). The Tai Chi group participated in an 18-week exercise class held for 45 min, twice a week. Body balance was assessed using a Computer Posturographic System PE 90 produced by the Military Institute of Aviation Medicine in Warsaw with modified software made in Pro-Med. During the measurement of body balance, the capacity to perform specific tasks was analyzed (deflections in the set scope and direction). In the Tai Chi group, an increase (p < or = 0.01) in effectiveness of balance task performance was noted from 80.95% to 84.45% after the training. In the control group, no statistically significant improvement in the level of body balance was found in the same period. Thus, an 18-week period of Tai Chi exercises twice a week for 45 min is beneficial for dynamic balance. It can be important for reducing fall risk factors.