Whole-cell patch clamp recording techniques were applied to periglomerular (PG) cells in slices of the frog olfactory bulb (OB) preparation to study the basic electrical properties of these inhibitory interneurons. The cells were intracellularly stained with Lucifer Yellow for precise identification. Under current-clamp conditions PG cells showed rich spontaneous excitatory synaptic activity at rest, usually leading to overshooting, TTX-sensitive action potentials. The passive cable properties of the cell membrane have been carefully characterised. Depolarisation of this neurone under voltage-clamp conditions activated a complex pattern of current flow, that has been dissected into its main components. The currents have been isolated resorting to their different kinetic and pharmacological properties. Four main voltage dependent ionic currents have been isolated, two inward currents, I(Na) and I(Ca), and two outward currents carried by potassium ions, one fast transient, I(A)-type and another similar to the delayed rectifier type. These currents have been characterised kinetically and pharmacologically. The functional implications of their properties are discussed.