Content of lipid hydroperoxides (LHP) and malonic dialdehyde (MDA) was measured in homogenates of rat brain cortex (limbic, sensomotor and orbital cortex) and subcortex brain structures (hypothalamus, medulla oblongata, and midbrain) and in their synaptosomal and mitochondrial fractions within various periods of starvation 1, 2, 3, 5 and 7 days. Lipid peroxidation was shown to intensify distinctly in the brain regions studied especially in the sensomotor cortex only after relatively long-term starvation during 5-7 days. The rate of lipid peroxidation was considerably higher in mitochondrial fractions of these brain structures studied than in the synaptosomes; high contents of LHP and MDA was found in mitochondria. Activation of lipid peroxidation appears to be distinctly responsible for impairment of the structure and functional components of nervous cells occurring during long-term starvation.