Abstract The aims of this study were to assess how stress affects chronic headaches, and in particular to determine whether events play a role in the transformation of an episodic headache into a chronic form. A population of 267 Italian patients with chronic headache (headache present on average more than 15 days per month) was studied. Our results confirm a triggering role of stress on headache. We also found that episodic headache (migraine in most patients, 74.1%) preceded the development of a chronic form in about 90% cases. Among these patients, in 44.8% a stressful event correlated with the transformation. Analysis of these events revealed that minor events played a greater role than major life events, suggesting that patients with transformed headache are characterised by a different way of reacting to stress.