Two field experiments were carried out to discuss the growth, development, yield and some forage constituents of five tropical and subtropical grass species in relation to the air temperature condition. At the high temperature condition, these grasses emerged early and showed the accelerated growth rate, the advanced growth stage, and accordingly the deterioration in the forage quality. The optimum seeding period was considered to be at the mean daily temperature of 16-18℃ (from late April to late May in Fukuoka district) and three times cutting until autumn was suitable for forage production. Green panic (Gp), the lowest in winter survival, produced the highest total dry matter, conversely, dallisgrass (Dg) and Bambatsi makarikarigrass (Bp), the highest in winter survival, were low in dry matter production. The wintering ability and the production of Kazungula setaria (Ks) and Gayndah Buffel grass (Bg) were intermediate between Gp and Dg or Bp. Dg and Bg was excellent in the forage quality and the latter was superior in the potentiality at a low temperature.