Finland is the only country in which summer turnip rape (Brassica rapa L.) is predominant over oilseed rape (Brassica napus L.) as an oil crop. However, farmer interest in growing oilseed rape has increased significantly over recent years. Accordingly, this study aims to compare the regional risks of producing turnip rape and oilseed rape in order to avoid setbacks in Finnish vegetable oil production. This study is especially topical because the cultivated area of Brassica oil crops is projected to double in the near future and recent years have particularly favoured oilseed rape production and farmers have been encouraged to replace turnip rape with oilseed rape. Using information gained through this risk assessment, changes in oil crop production can be managed in a more economically sustainable way. In this study we used long-term datasets from MTT Agrifood Research Finland (MTT Official Variety Trials for 1976–2005) and the Finnish Meteorological Institute (regional datasets for temperature accumulation and occurrence of frosts at late seed ripening for 1971–2000). According to the results of this risk assessment, sustainable and economically feasible oil crop production in Finland must currently be based primarily on turnip rape. Oilseed rape is, however, likely to become increasingly important, but in the most favourable fields of the southernmost production regions. However, it was evident that comparison of yield values is very sensitive to variety differences for the most critical yield parameters. Hence, when introducing new oilseed rape varieties it is particularly important that they always have equal or better seed yield and seed chlorophyll content than the recently introduced, markedly improved oilseed rape varieties. This will reduce economic risks for farmers.