ABSTRACT The microtubules of root hairs of Raphanus sativus, Lepidium sativum, Equisetum hyemale, Limnoblum sloloniferum, Ceratopteris thalictroides, Allium sativum and Urtica dioica were inves-tigated using immunofluorescence and electron microscopy. Arrays of cortical microtubules were observed in all hairs. The microtubules in the hairs show net axial orientations, but in Allium and Urtica helical microtubule patterns are also present. Numerical parameters of microtubules in Raphanus, Equisetum and Limnobium were determined from dry-cleave preparations. The results are discussed with respect to cell wall deposition and cell morphogenesis.