Computer simulations were conducted to investigate the effects of solar radiation enhancement on the cultivated area in a Chinese style lean-to greenhouse. The results showed that, under both direct and diffuse radiation, a more uniform distribution and increased amount of reflected radiation on the cultivated area could be obtained by installing a reflector [either an aluminized reflector or a polyvinylchloride (p.v.c) film sheet] from the ridge down to the ground [arrangement (b)] than by installing it on the interiors of the north wall and roof [arrangement (a)]. Moreover, to overcome the uneven distributions of the daily transmissivity of direct radiation when installing an aluminized reflector vertically from the ridge down to the ground, caused by the second reflection during winter months at 40ยฐN and 45ยฐN, an improved method was adopted. This method involves manipulation of the inclination angle of the aluminized reflector according to the solar altitude in such a way that the reflected light beam from the top of the reflector reaches the southern edge of the cultivated area at any time [arrangement (c)]. The analytical results indicated that not only the distribution uniformity, but also the total amount of reflected radiation on the cultivated area was marginally improved through this adjustment. When using the aluminized reflector under direct solar radiation, values of daily reflected radiation were 0)526 for arrangement (a), 0)691 for arrangement (b) and 0.712 for arrangement (c). Consequently, values of total solar radiation (incident#reflected) reaching the cultivated area were 1)276 for arrangement (a), 1)441 for arrangement (b) and 1)462 for arrangement (c). Similar results were obtained under diffuse radiation.