A simple, defined medium has been standardized for the mass multiplication and production of virus-free plants of Pogostemon cablin (Blanco) Benth. Shoot meristems cultured on Murashige and Skoog's (1962) medium (MS) supplemented with 2.0 mg I-1 6-benzylaminopurine (BAP) or 0.5-2.0 mg I-1 6-?,?dimethylallyaminopurine (2iP) or 0.5-2.0 mg I-1 zeatin (Z) and 1.0 mg I-1 indole-3-acetic acid (IAA) exhibited multiple shoot proliferation. Regenerated shoots readily rooted on half-strength MS containing 1.0 mg I-1 IAA or ?-naphthaleneacetic acid (NAA) and 1.5% sucrose. Rooted plantlets were transferred to pots, hardened in the glasshouse and grown to maturity in the field with a high rate (80-90%) of survival. Plant tests made for patchouli mosaic virus (PaMV) with leaf extracts of plants developed in vitro from the fifth subculture passage onwards gave a negative reaction in diagnostic tests on the local lesion host plant, Chenopodium quinoa Willd., demonstrating the absence of the causal agent in plants regenerated from the shoot meristems.