The uptake and distribution of Ca in white cabbage have been measured under controlled climatic conditions. The uptake of Ca has been determined by continuous β-intensity measurements of45Ca simultaneously at an outer transpiring leaf and at an inner head leaf. In the outer leaves the Ca content increased during the day in dependence of the transpiration amplitude. With-in the inner head leaves Ca was transported mainly during the night when the head mass additionally measured by γ-absorption increased due to the increasing plant water potential. At the end of the experiment the stable and active Ca concentration has been measured.