Cuttings from 20 Lotus corniculatus L. individuals were inoculated with Rhizobium and grown under one of three nitrogen regimes, including a treatment where plants relied solely on symbiotic N-fixation. Plants of a single genotype were then grouped so that Spodoptera eridania Cramer larvae could chose to feed among plants from the different N-treatments for a 3 1/2-week period. Shoot and root biomass, condensed tannin and cyanide concentration, astringency, flower, fruit and seed number and fruit biomass were measured in damaged and undamaged plants when flowering had ceased (3 weeks after herbivory ceased). Larvae did not appear to exert a choice among the different nitrogen treatments. N-fertilized plants had larger shoots, larger roots and more seeds than N-fixing plants. Astringency and both protein and cyanide concentrations were not influenced by treatment. Damaged plants were lower in shoot biomass and seed production, but had larger root biomass and higher protein concentrations. Tannin concentrations appear to have been induced in damaged plants, while cyanide concentrations were not influenced by herbivory.