Crop-based protein self-sufficiency in Finland is low. Cereals dominate the field cropping systems in areas that are also favourable for legumes and rapeseed. The present paper estimated the realistic potential for expanding protein crop production taking account of climatic conditions and constraints, crop rotation requirements, field sizes, soil types and likelihood for compacted soils in different regions. The potential for current expansion was estimated by considering climate change scenarios for 2025 and 2055. By using actual regional mean yields for the 2000s, without expecting any yield increase during the expansion period (due to higher risks of pests and diseases), potential production volumes were estimated. Since rapeseed, unlike grain legumes, is a not a true minor crop, its expansion potential is currently limited. Thus, most potential is from the introduction of legumes into cropping systems. The current 100000 ha of protein crops could be doubled, and areas under cultivation could reach 350000 and 390000 ha as a result of climate warming by 2025 and 2055, respectively. Such increases result mainly from the longer growing seasons projected for the northern cropping regions of Finland. Self-sufficiency in rapeseed could soon increase from 0·25 to 0·32, and then to 0·50 and 0·60 by 2025 and 2055, respectively. If legume production expands according to its potential, it could replace 0·50–0·60 of currently imported soybean meal, and by 2025 it could replace it completely. Replacement of soybean meal is suitable for ruminants, but it presents some problems for pig production, and is particularly challenging for poultry.