Myofibroblasts are mesenchyme-derived cells responsible for tissue repair after injury. Resident populations of myofibroblasts are present throughout the lung. In addition, it is likely that myofibroblast progenitors (fibrocytes) can migrate to the lung from the circulation during injury. The relationship and interdependencies among myofibroblasts, fibroblasts, and myocytes within the airway wall remain poorly understood. Myofibroblasts are likely to be present in primary culture systems derived from airway wall tissue. The phenotyping of cells in such cultures is complicated by the lack of specific markers for these cell types. Important responses including migration, synthetic function, and the regulation of matrix, in the normal and asthmatic airway previously considered to be driven by airway myocytes may in fact at least in part be due to responses of myofibroblast populations.