Quoirin & Lepoivre medium contains the macro- and micronutrients as described by Quoirin & Lepoivre (1977) and Quoirin, et al. (1977). Quoirin & Lepoivre medium has been specially formulated for plant cell, tissue and organ cultures. Ammonium nitrate and potassium nitrate serve as nitrate sources. Medium does not contain sucrose and agar ; hence, these components have to be added to the medium before use. Prunus species plantlets could be regenerated from root callus on a medium defined by Quirin and Lepoivre. The calli were formed on the roots of plantlets derived from meristem culture containing 6-benzylaminopurine and Gibberellic acid. Quoirin & Lepoivre medium has several differences in comparison to Murashige & Skoog medium. The ammonium ion concentration is strongly reduced, the calcium ion concentration is -increased and the chlorine ions are almost eliminated. This formulation avoids vitrification problems.