Nezasa bamboo (Pleioblastus variegatus Makino) is an important native plant for grazing of beef cows in the grasslands of Aso area. In 1992 nezasa bamboo flowered over 2,150 ha of grassland in the northern somma of Aso volcano. The current studies were carried out to investigate the effects of flowering on yearly changes in the above- and underground parts of nezasa bamboo. In the flowering year (1992) the amount of aboveground parts (44.0 g DM m^-2 in June 1992) decreased to 19% of the value recorded (227.1 g DM m^-2 in June 1991) in the previous year (1991). In the year after flowering (1993), the aboveground parts were scarce (only 1.3 g DM m^-2 in June 1993). Dry matter weight of underground plant parts in the year of flowering decreased from spring to autumn, and the plants died after the summer. In the next year of flowering the dry matter weight continued to decrease. In 1994, the recovery of nezasa bamboo in grasslands of the northern somma of Mt. Aso was investigated. The rate of recovery was low and it was considered that 10 or more years would be required for the recovery of nezasa bamboo.