Systemic acquired resistance, which results in enhanced defense mechanisms in plants, can be elicited by biotic or abiotic factors such as pathogens causing a hypersensitive necrotic reaction, virulent and avirulent pathogenic strains, and certain chemicals. Induced resistance against plant-parasitic nematodes has been documented, but is not as well understood as induced resistance to other pathogen groups. Split-root experiments conducted on susceptible, reniform resistant and root-knot resistant cotton showed that prior infection with one nematode species could induce systemic resistance against the other nematode species. The rate of nematode reproduction was evaluated to quantify the level of systemic acquired resistance. In a different project, infection by reniform and root-knot nematodes systemically enhanced the activities of pyrogallol peroxidase, guaiacol peroxidase and catalase enzymes in the leaves of cotton plants. This study documents for the first time that infection of cotton by a nematode can elicit enhanced defense to another nematode species through induction of systemic acquired resistance.