A general problem for the technical applications of magnesium alloys is their low corrosion resistance. One important possibility to improve the corrosion behaviour of magnesium alloys is the development of suitable protective coatings. The use of chromate will be no longer desired due to some legal regulations. However, plasma CVD (chemical vapour deposition) processes opens new possibilities for the pretreatment and coating of magnesium alloys. Compared to other chromium free pretreatments magnesium alloys could be improved in their corrosion resistance by using the method of combining water chemical degreasing, chemical pickling and a plasma CVD process.