The hyperpolarization-activated cyclic nucleotide gated (HCN) channels are voltage-gated ion channels that are active at rest and are important for determining the intrinsic membrane properties of neurons. Four HCN subunits (HCN1-4) have been cloned, with HCN1 predominantly expressed in the cortex. These subunits are abundant in cortical pyramidal neuron dendrites but can also be located in synaptic terminals and axons. In this lecture, I will highlight work on the involvement of these channels in dendritic excitability, synaptic release and epileptogenesis in the entorhinal cortex (EC), an area of the brain involved in normal physiological processes such as spatial navigation and cognition as well as pathophysiological conditions such as epilepsy. I will also present work on the distinct molecular mechanisms underlying trafficking of these channels to dendritic and pre-synaptic compartments. This lecture should, thus, provide an insight into the role of these channels in regulating cortical neuronal function and the potential consequences of this for cognition and epilepsy.