Objective: The purpose of this article is to compare the morphological changes induced by acute immobilization with thoseproduced by chronic immobilization, in vermal cerebellar cortex of young male sprague dawley rats. Study design: Experimental study.Setting: Department of Anatomy CPSP Regional Centre, Islamabad. Period: 2005 to 2007. Material and method: A total of 120 young maleSprague Dawley rats were taken and divided equally in two groups for acute and chronic immobilization stress. Both these groups were dividedfurther into two subgroups (n=30 in each) control acute, experimental acute, control chronic and experimental chronic. ‘Experimental acute’group Ib was kept in restrainer for 24 hours continuously while ‘experimental chronic’ group IIb was kept in restrainer for 2 hours daily forfourteen days, one rat per restrainer separately. Hematoxylin and Eosin stained sections were studied under light microscope to record thedata. Results of experimental acute group were compared with those of experimental chronic’. Data was analyzed by SSPS version 10.Results: Insignificant increase in thickness of vermal cerebellar cortex and molecular layer was found in both acute and chronically stressedrats; but comparatively more in group Ib, however minimal non significant change in granular layer was seen in both experimental groups.Conclusions: Immobilization stress can cause the neuronal injury. Acute stress tends to produce more severe effects on brain cortical tissueas compared with chronic stress. The reason for occurrence of less severe effects under chronic stress is probably due to role of thephenomena of adaptation.