This paper contributes to the historiographical debate about the impact of forced labour in the Spanish economy within the context of Civil War and immediate post‐war. Despite the advances made by historians, some key factors (such as the workforce supply‐demand, the costs and benefits of the different kind of workers, the levels of productivity, or the legal framework) must be taken into account in order to understand to which extent the state and the private companies were interested in recruiting forced labourers. Besides, in the Spanish case it is yet needed to draw an exhaustive map of the impacts of forced labour, signalling the important differences according to chronology and productive sectors. This paper advances in that direction from a regional perspective, analyzing the impact of forced labour in the Basque‐Navarre economy. The data show an important growth of forced labour over the years of the war economy, and a fast decline in the post‐war. Nevertheless, important differences between leader sectors of Basque economy are revealed: while in the steel industry and iron mines by 1939 forced labourers were almost inexistent, in military and transport infrastructures (such as opening mountain roads and airports) forced labourers maintain their prominence at least until the end of 1942.