Forty-three near-isogenic lines (NILs) of white clover (Trifolium repens), derived from four parental self-compatible genotypes containing the rare self-fertility allele, were inoculated with the arbuscular mycorrhizal fungus Glomus mossae. Plant growth response (shoot and root weight and root length), shoot P uptake and mycorrhizal root infection rates were recorded 12 weeks after inoculation. There was generally a high degree of variation between individual lines in all recorded parameters. The most sensitive indicator of plant response to mycorrhizal infection was root length with almost half of all lines showing significant responses (in most cases a decrease in root length). Shoot weight was significantly different between mycorrhizal and nonmycorrhizal plants in nine lines. Parental genotype significantly affected both plant response to mycorrhiza as well as mycorrhizal infection rates. The results suggest that the NILs will prove useful for further studies to elucidate the molecular genetic control of the symbiosis and inform plant breeding strategies of this agronomically important species.