Objective- Locomotor disorders are prevalent health problems in dairy herds that negatively affect milk production, reproduction performance and animal welfare. The ultimate cost of locomotor disorders in dairy cattle is substantially greater than treatment costs alone. As limited information is available on incidence of feet and leg disorders in Iran, the objective of this study was to determine cumulative incidence of locomotor disorders in dairy herds of Tehran province. Design- Historical cohort study Study population and procedures- Totally, 10506 Holstein cows, from 32 Iranian dairy herds, which calved from March 2007 to March 2008, were followed until the next calving or culling and cumulative incidence of locomotor disorders was calculated based on registered data. Results- Cumulative incidence of locomotor disorders in the studied cows was 23.2% (95% CI: 22.4- 23.9). This index was 20.0% (18.7-21.2), 19.6% (18.2- 21.0), 29.3% (27.1-31.5), 29.3% (27.1-31.5), 35.6% (31.6-49.3) and 23.8% (19.2-28.4) in the first to sixth and more than sixth lactation, respectively. This showed, locomotor problems are important issue in this area. Moreover, with increasing parities cumulative incidence of locomotor disorders increased; this increase could be due to weight gain, increased milk production and culling susceptible animals to these health disorders before sixth lactation. Conclusion and Clinical Relevance- Our findings confirm the results of previous studies that dairy herd-health programs should emphasize the control of feet and leg disorders.