The study investigates the role of hyperpolarization-activated currents (I_h) in modifying the integrative properties of hippocampal CA1 pyramidal neurons. Step hyperpolarizations evoke slowly activating, noninactivating, and slowly deactivating inward currents from membrane patches in the soma and apical dendrites. The density of these currents increases significantly from the soma to distal dendrites, with a sixfold increase over the somatodendritic axis. I_h channels are voltage- and temperature-dependent, and their activation and deactivation kinetics are influenced by hyperpolarization and depolarization, respectively. I_h is a mixed Na^+-K^+ conductance and is sensitive to low concentrations of external CsCl. Dual whole-cell recordings reveal regional differences in input resistance (R_in) and membrane polarization rates (r_mem) across the somatodendritic axis, which are attributed to the spatial gradient of I_h channels. These differences affect the propagation of subthreshold voltage transients and action potentials. The elevated dendritic I_h density reduces EPSP amplitude and duration, and the time window for temporal summation. Action potential backpropagation into the dendritic arborization is slightly impacted by dendritic I_h, primarily affecting the duration of dendritic action potentials and the afterhyperpolarization. Overall, I_h dampens dendritic excitability, particularly in the subthreshold range of membrane potentials where synaptic integration occurs.The study investigates the role of hyperpolarization-activated currents (I_h) in modifying the integrative properties of hippocampal CA1 pyramidal neurons. Step hyperpolarizations evoke slowly activating, noninactivating, and slowly deactivating inward currents from membrane patches in the soma and apical dendrites. The density of these currents increases significantly from the soma to distal dendrites, with a sixfold increase over the somatodendritic axis. I_h channels are voltage- and temperature-dependent, and their activation and deactivation kinetics are influenced by hyperpolarization and depolarization, respectively. I_h is a mixed Na^+-K^+ conductance and is sensitive to low concentrations of external CsCl. Dual whole-cell recordings reveal regional differences in input resistance (R_in) and membrane polarization rates (r_mem) across the somatodendritic axis, which are attributed to the spatial gradient of I_h channels. These differences affect the propagation of subthreshold voltage transients and action potentials. The elevated dendritic I_h density reduces EPSP amplitude and duration, and the time window for temporal summation. Action potential backpropagation into the dendritic arborization is slightly impacted by dendritic I_h, primarily affecting the duration of dendritic action potentials and the afterhyperpolarization. Overall, I_h dampens dendritic excitability, particularly in the subthreshold range of membrane potentials where synaptic integration occurs.