Abstract 1. 1. Extracellular recordings were made from Purkinje cell layer of rat cerebellar slices. Cell activity was sensitive to both magnesium and manganese ions. 2. 2. Glutamic and aspartic acids both excited cell activity while γ-aminobutyric acid (GABA), muscimol, taurine, β-alanine and δ-aminolaevulinic acid all inhibited activity. 3. 3. The sensitivity to GABA varied with depth while no such effect was observed with muscimol. 4. 4. Bicuculline methiodide, picrotoxin and pitrazepin blocked the action of muscimol with pA 2 values of 5.92, 5.97 and 5.71 respectively. 5. 5. The benzodiazepines flurazepam and RU 32007 both potentiated the GABA inhibition and this potentiation was blocked by Ro 15–1788, a benzodiazepine antagonist.