The cerebral compression and edema were successfully produced by the expansion of the stalk of laminaria in the right epidural space of the rabbits. By weighting the wet and dry brain tissues, and by calculating the percentage of water content and that of swelling, with the rate of per cent water content to that of control group, the studies of the occurrence and changes of experimental brain edema have been observed. In the normal rabbits, the average per cent water content of cerebral gray and white matters were 79.9+/-0.7% and 73.0+/-1.0% respectively. The percentage of water content and swelling of cerebral gray and white matters in the compression site showed higher values than those in control group. As compared with normal group, the rate of per cent water content of cerebral gray matter at the site of compression showed gradual increasing tendency as time elapsed by 24 hours, while that of white matter demonstrated rapid increased of it by 6 hours and decreased gradually thereafter. And it appeared that the value of the cerebral white matter showed higher than that of gray matter throughout the period of 24 hour's compression. Cereral edema induced by laminaria compression was more evident and severe in the white matter than in the gray, which was more striking at the early stage of cerebral compression.