KCNQ1 and KCNQ4 voltage-gated potassium channel subunits play key roles in hearing. Other members of the <i>KCNQ</i> family also encode slow, low voltage-activated K⁺ M currents. We have previously reported the presence of M-like K⁺ currents in sensory hair cells, and expression of <i>Kcnq </i>family genes in the cochlea. Here, we describe <i>Kcnq2/3</i> gene expression and distribution of M channel subunits KCNQ2 and 3 in the cochlea. By using RT-PCR, we found expression of <i>Kcnq2</i> in the modiolus and organ of Corti, while <i>Kcnq3</i> expression was also detected in the cochlear lateral wall. Five alternative splice variants of the <i>Kcnq2 </i>gene, one of which has not been reported previously, were identified in the rat cochlea. KCNQ2 and KCNQ3 immunoreactivities were observed in spiral ganglion auditory neurons. In addition, the unmyelinated parts of the nerve fibers innervating hair cells and synaptic regions under hair cells showed KCNQ2 immunoreactivity. KCNQ3 immunoreactivity was also prominent in spiral ganglion satellite cells. These findings suggest that cochlear M channels play important roles in regulation of cellular excitability and maintenance of cochlear K⁺ homeostasis in the auditory system.