The root organic matter (OM) per unit volume of soil ofLolium perenneL. (perennial ryegrass) was evaluated over two years under subtropical conditions. Root OM was measured on five separate occasions in four soil-depth categories (0–50, 50–100, 100–200 and 0–200 mm) under six combinations of grazing frequency and intensity. The root systems were unaffected by treatments during the establishment year. During the second year, treatments infrequently grazed had higher root OM contents per unit volume of soil in both the 0-50- and 0-200-mm soil-depth categories than treatments frequently grazed. Grazing intensity did not affect root OM per unit volume of soil in any depth class. Overall, perennial ryegrass was found to be shallow-rooted, with approximately 75% of the root mass occurring in the top 50, mm of the soil.