Purpose:
To describe and illustrate the spectrum of magnetic resonance imaging (MRI) findings of tibial stress injuries (TSI) and propose a simplified classification system.

Material and methods:
Retrospective analysis of MRI exams of 44 patients with clinical suspicion of unilateral or bilateral TSI, using a modified classification system to evaluate the intensity and location of soft-tissue changes and bone changes.

Results:
Most of the patients were young athletic men diagnosed in late stage of TSI. Changes were predominantly found in the middle and distal parts of tibias along medial and posterior borders.

Conclusions:
TSI may be suspected in young, healthy patients with exertional lower leg pain. MRI is the only diagnostic method to visualise early oedematic signs of TSI. Knowledge of typical locations of TSI can be helpful in proper diagnosis before its evolution to stress fracture.