Introduction Normal defaecation is dependent upon activation of anorectal mechanoreceptors, which respond to pressure and stretch. Evoked potentials (EPs) have been used to interrogate these pathways but are typically recorded in response to non-physiological electrical stimuli, known to directly depolarise nerve fibres without receptor activation. However, the use of a mechanical stimulus should provide a more physiological assessment of these pathways. This study compared EPs elicited via mechanical and electrical stimulation of the rat anal canal. Methods In fourteen anaesthetised (urethane i.p., 1g/kg) female Wistar rats (body mass 180 – 270g) mechanical and electrical EPs were recorded using a 32 channel multi-electrode array placed over the right primary somatosensory cortex. Stimulations for electrically elicited EPs were applied with a 2mm anal plug electrode (1Hz, 1ms, 10V) and mechanical stimuli via an inter-dental brush placed on a rotating stepper motor (1Hz, 1ms, 15o rotation). Response latency, response amplitude and activated spatial extent (expressed as an index) were evaluated. A P value of <0.05 was considered to be statistically significant. Results Mechanical and electrical EPs were recorded successfully in all animals. Mean maximal response amplitude (electrical 25.9µV (SD 22.2) vs. mechanical 19.3 µV (12.6)) and onset latency (electrical: 13.8ms (2.6) vs. mechanical: 14.2 ms (2.2)) were similar (Student’s t-test P = 0.25 and P = 0.62). Cortical location and waveform profile were also similar. An activated spatial extent index was significantly lower for mechanical stimulation (2.1 (1.4) vs. (4.5 (2.4), Mann-Whitney U-test P = 0.0015). Figure 1 illustrates this in one animal as a colour map encoding the maximal amplitude for each channel. Conclusions To the authors’ knowledge these are the first mechanically elicited anal EPs recorded in animals. Cortical responses to mechanical stimulation appear to be more focal, a finding which may reflect more selective activation of ascending sensory pathways. Mechanical EPs may prove useful in the further exploration of treatments that modulate the neuronal control of defaecation such as sacral nerve stimulation.