Objective To observe the characteristics of pupillary light reflex in the patients with retrobulbar neuritis, and to evaluate the effects of pupi llary light reflex on the diagnosis and treatment of retrobulbar neuritis. Methods Thirtyfive patients (thirtyfive eyes with the retrobulbar neuritis and thirtyfive fellow eyes) aged from 10 to 58 years and 50 healthy individuals (100 eyes) who didnlsquo;t differ from the patients in age and sex were examined by a automatic pupillometer. The pupillary area and response amplitude, latency and speed of papillary reflex were recorded. Results The latency of the pupillary light reflex delayed and the maximum amplitude decreased in patients with retrobulbar neuritis during the diseas eperiod, and the differences were highly significant compaired with the control group. After the treatment, as the symptoms were alleviated and the visual acuity improved, the latency of the pupillary light reflex and the maximum amplitude recovered. The statistic differences were both found between the results after treatment and those at the onset stage, and the results after treatment and those in the control group.Before the onset of the disease of the involued eyes and after the treatment, the papill ary light reflex and the maxium amplitude decreased, but didnamp;#146;t differe much from which in the control group. Conclusions The latency of the pupillary light reflex delayes and the maximum amplitude decreases in patients with retrobulbar neuritis. The examination of pupillary light reflex is helpful to diagnose retrobulbar neuritis early and inspect the condition of the disease. (Chin J Ocul Fundus Dis,2006,22:370-372)