Contrast sensitivity functions for sinusoidal gratings of different spatial frequencies and stimulus durations were determined for both eyes of amblyopic [human] subjects. For both long and short stimulus durations, the entire contrast sensitivity function of the amblyopic eyes was lower than that of the nonamblyopic eyes. When the gratings were flickered at 10 Hz, the sensitivity for pattern and flicker detection were similar for both eyes at low spatial frequencies. Possible neural mechanisms for the differences in contrast sensitivity were considered with respect to recent psychophysical and electrophysiological evidence for channels with different spatio-temporal properties in the mammalian visual system.