Abstract Background: Pneumomediastinum creation, in blunt chest trauma, results from Mackin effect in more than 95% of cases. Objectives: In this article we report two cases of blunt chest trauma, underlining the relationship between Macklin effect, pneumomediastinum and pneumoperitoneum, and analysing conservative and invasive treatment. Case reports: We report two cases of blunt chest trauma with Pneumomediastinum creation and no evidence of airway lesions. The first patient presented with malignant pneumomediastinum, created by Macklin effect, and pneumoperitoneum with intra-abdominal hypertension. He underwent invasive treatment. The second case shows how Macklin effect can be self-limiting. This patient underwent conservative treatment. Conclusions: In any case of post-traumatic pneumomediastinum, the Macklin effect should be suspected. Clinical observation is the treatment of choice since Macklin effect is self-limiting. There are some life-threatening event, like malignant pneumomediastinum and intra-abdominal hypertension that must be relieved and treated mmediately
