Provitamin D2(ergosterol), vitamins D2and D3reduced the calcium‐mediated peroxidase secretion in three types of sugarbeet cells in suspension cultures. Vitamin D2was the most effective in habituated non‐organogenic cells which were the less sensitive to calcium; provitamin D2was the most effective in habituated organogenic cells, while normal non‐organogenic cells were equally sensitive to the three types of vitamin D. The calcium ionophore A23187 slightly restricted peroxidase release in all cases, except in the habituated organogenic cells in the presence of calcium where it exerted a promotive effect. The inhibiting effect of vitamin D2was not counteracted by the ionophore except in this habituated organogenic cell