This paper analyses the increase in forest surface covered by trees in Spain in the second half of the twentieth century in the light of Forest Transition Theory and explores the existence of a statistical relationship between this process and the extension of forest fires. The study describes the afforestation policy based on new forest plantations started by Franco´s regime in 1940 which surpassed the chronological limits of the dictatorship and lasted until 1988, linking it to the forest fires that occurred in the period 1968-2002. The objective is to determine, at a provincial level, the extent to which the afforestation activity affected the number of hectares burnt. The evidence shows a significant positive relationship between forest fires and the afforested hectares, especially 30-35 years after plantations. The effect increases when the model is implemented exclusively for the Cantabrian and Atlantic northwest provinces, especially affected by afforestation programmes. Our findings reinforce the need to complement certain models of Forest Transition based on tree plantations, taking into account the possible relationship that they have with fires, particularly in environmental contexts prone to fires.