Parvalbumin (PV) is expressed in a small proportion of spinal dorsal horn neurons in both the rat and mouse. In the rat, approximately 70% of PV-immunoreactive (-ir) cells in laminae II and III are inhibitory neurons. These comprise a heterogeneous population of cells that contain GABA only, glycine only, or both GABA and glycine, and each sub-population may represent a subtle, functionally distinct class of interneuron. The aims of this study were to i) compare the distribution, morphology and neurochemical phenotype of parvalbumin-expressing neurons in the superficial dorsal horn of rats and mice; ii) determine the main afferent inputs on to these PV-ir cells; iii) identify the postsynaptic targets of these PV-ir cells. Adult male Wistar rats and ICR mice were terminally anaesthetised by i.p. injection of sodium pentobarbitone prior to perfusion fixation. Transverse or sagittal sections from lumbar segments of the spinal cord were first incubated in a cocktail of primary antibodies and then species-specific secondary antibodies tagged with fluorescent markers to reveal labelling for parvalbumin, vesicular GABA transporter, vesicular glutamate transporter 1 (VGLUT1), IB4, CGRP, HCN channel subunits and PKCγ. Confocal image stacks were collected from representative sections of each animal to determine the morphology of PV-ir cells, the relationships of their axons with primary afferent terminals, the main primary afferent input onto these cells and the proportion of PV-ir cells expressing HCN channel subunits. Image stacks were analysed using Neurolucida image-analysis software. Although the main plexus of PV-ir cells in the rat and mouse dorsal horn was found in lamina II inner (IIi) and III respectively, the main plexus of PV-ir axons of either species arborised in lamina IIi. PV-ir cells in both species often displayed islet cell-like morphology, with large cell bodies and elongated dendritic arbors extended in the rostro-caudal axis. These cells often expressed immunolabelling for HCN channel subunits, suggesting that PV-containing neurons show Ih currents and display tonic discharge patterns. The main primary afferent input on to these cells comes from IB4-positive terminals, while inhibitory PV-ir axon terminals target VGLUT1-ir axon terminals in lamina IIi almost exclusively. These results suggest that PV-containing neurons in the superficial dorsal horn of both rats and mice comprise very similar populations. They also show that PV-containing neurons are likely to include islet cells, receive strong afferent input from non-peptidergic C-fibres, are likely to show Ih currents and display tonic discharge patterns, and mediate presynaptic control over myelinated primary afferents from low threshold mechanoreceptor and down-hair afferents.