Pollen tubes from germinated Petunia pollen were prepared in different ways for electron microscopic investigation of their walls. The ultrastructural features of the tube walls depend strongly on the preparation methods used. The tube wall was found to be composed of two layers or appeared striated after fixation with KMnO* and 0s04, respectively. After freezeetching the tube wall is twice as thick as after chemical fixation and a fine striation is visible. Subsequent extractions dissolve the matrix substances and a network of microflbrils is left, which is not composed of lamellae.