Imaging plays an integral role in the diagnosis of lumbar pars bone stress injury due to the limited sensitivity of clinical history and physical examination. Its use has evolved over the decades from plain radiography, CT and bone scintigraphy, which all involve the use of ionising radiation, to the present day, where MRI alone allows accurate demonstration of pars bone stress injury and fracture, without the use of ionising radiation. The lack of radiation means that follow-up scans to assess healing can be performed safely. Early identification of lumbar bone stress injury, with appropriate activity modification, maximises the likelihood of injury healing and can prevent progression towards pars fracture non-union. Progress imaging has a role in monitoring healing and deciding on return to play. Healing of incomplete and complete fractures is much more likely for unilateral lesions, again increasing the value of early diagnosis.