The interaction of various types of liposomes with protoplasts of Nicotiana tabacum and Capsicum annuum was studied by means of fluorescence microscopy and autoradiography. The liposomes with a positive charge displayed the strongest affinity to the protoplast membrane, whereas the maximum intracellular delivery of encapsulated protein and DNA molecules into protoplasts was exhibited by the negatively charged liposomes. The results showed that the negatively charged unilamellar liposomes prepared by the reverse-phase evaporation method represent a very promising universal vehicle system for introducing genetic information into plants.