Red, blue and white stimulus strips were repeatedly presented for I5 sec., with I5 sec. pauses between trials, to three different groups (N=I0, I0 and I8, respective) of two-day old herring gulls. The pecking response to these colours gradually extinguished, requiring I2I, 55 and 36 pecks in the respective group until the criterion (three consecutive trials of zero frequency) was reached. Since the blue and the red group revealed similar pretest frequency (before extinction) there was evidence for a flatter regression to the red stimulus. This was further supported by the similarity between the blue and the white group on other parameter values during extinction. The finding was taken as a partial explanation of the divergent results obtained earlier concerning the peak colour preference in this species; investigations build around repeated stimulus presentations would favour a red preference. A test stimulus of different colour presented after complete extinction gave rise to a strong disinhibition of the response. There was a limited degree of stimulus generalization evident through disinhibitional effects toward darker achromatic stimuli presented after extinction to the white stimulus. The response showed an exponential rate of spontaneous recovery, reaching the original strength within about three hours. In general, the pecking response showed characteristics during extinction in common with responses studied hitherto.