A novel lysozyme from cauliflower was purified in a single step, for the first time, using Sephadex G100 column chromatography. The purified lysozyme exhibited a homogenized single band in sodium dodecyl sulfate polyacrylamide gel electrophoresis (SDS-PAGE), and its molecular mass was calculated to be 22.0 kDa. The purified lysozyme showed activity between 30 to 60 A degrees C with 40 A degrees C as the optimum temperature for its maximal activity. Although the purified lysozyme was functional at pH ranges between 3.0 and 9.0, the optimum pH for the enzyme activity was 8.0. By Michaelis-Menten equation, the threshold substrate concentration for the optimal enzyme activity was calculated to be 133.0 mu g. The purified lysozyme showed extraordinary activity against plant pathogenic bacteria and fungi. At 10-mu g concentrations, it inhibited the growth of plant pathogenic bacteria such as Pseudomonas syringae, Xanthomonas campestris, and Erwinia carotovora exhibiting 4.28, 5.90, and 3.88-fold inhibition, respectively. Further, it also completely inhibited the conidial germination of Archemonium obclavatum and, to a very large extent, other fungal species such as Fusarium solani (79.3 %), Leptosphaeria maculans (88.6 %), Botrytis cinera (73.3 %), Curvularia lunata (68 %), Rhizoctonia solani (79.6 %), and Alternaria alternata (83.6 %).