Abstract: A headlight assembly including a pair of headlight units each having first and second headlights. The first headlight has a halogen bulb having a high-beam filament for illuminating a range faraway from the vehicle and an auxiliary low-beam filament for illuminating a range in the vicinity of the vehicle. The second headlight has a discharge bulb for a low-beam for illuminating a range in the vicinity of the vehicle. The headlight assembly further includes a lighting control circuit for controlling lighting and turning-off of these headlights in such ways that both the bulbs of the first and second lamps are lighted during main lighting which illuminates the range faraway from the vehicle with a high-beam and the range close to the vehicle with a low-beam, that the bulbs of the second headlights are lighted during dimmer lighting which illuminates the range in the vicinity of the vehicle with a low-beam, and that only the bulbs of the first headlights are lighted during passing.