Mustard (Brassica campestris) is an important spice and oil plant. Seed yield and oil quality of mustard vary depending on genetic, ecological, morphological, physiological, cultural, and environmental factors and their interactions. Increasing obtained seed or oil yield as the final product is of great economic importance. One of the innovative and environmentally friendly methods for increasing the efficiency and quality of plant production is magnetic field applications. Mustard varieties 'Tori' and 'Sarson' were used in the study to reveal their performances under the effect of magnetic field (MF) treatments. The seeds of 'Tori' and 'Sarson' varieties were exposed to 150 mT MF strength for different time periods (0-control, 24, 48 and 72 hours). In 'Tori' variety, the highest seed and crude oil yields were obtained in 24-hour-MF treatment as 165.18 kg da-1 and 58.97 kg da-1, respectively, by an increase of 43.39% and 38.72%, respectively, according to control treatment where no MF was used. In variety 'Sarson', seed and crude oil yields were recorded as 210.39 kg da-1 and 78.9 kg da-1, respectively, as the highest in 48-hour-MF treatment by an increase of 54.03% and 44.4%, respectively, according to control. This study reveals that MF treatment increased seed and crude oil yields in mustard, and the protocol could make significant contributions to the yields of other crop plants.