After deafferentation of the septofimbriate introitus to the rabbit hippocamp acetylcholinesterase activity lowers in homogenates and usbcellular fractions within different areas of the hippocampal formation and subiculum. The greatest decrease is observed in homogenates of the denticulate fascia (up to 25% of the norm). In the subcellular fractions the greatest decrease is observed in the activity of the coarse mitochondrial and MHN-20 fractions as compared to the nuclear and microsomal ones. When separating the coarse mitochondrial fraction within the linear gradient of sucrose density (0.7--1.6 M), the greatest decrease in acetylcholinesterase activity is observed in the upper layers of the gradient. Distruction of septohippocampal relations produces a strong drop in the activity of butyryl cholinesterase and lactate dehydrogenase in the fimbria homogenates.