Roots of radish (Raphanus sativus L. var. radicula Pers.) of Rowa cv. seedlings grown in water cultures (pH 4.3) have been tested. Aluminum as AlCl₃·6H₂O has been applied at 0, 10, 20 and 40 mg·dm⁻³ concentrations. Inhibition of the growth of root elongation and the following changes of root morphology have been observed after aluminum treatment: browning and thickening, root cap elongation or falling off, bending of the apex root and cracks on its surface. Roots have been characterized with the change of hair length and lateral zones. First lateral roots occurred closer to the basal root apex than first hair. Reduction of hair length was noticed too. Atrophy of outer root tissues has been accompanied by great enlargement of cortex cells size as a result of their hypertrophy.