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5‐Hydroxytryptamine (5‐HT) activates colonic splanchnic afferents, a mechanism by which it has been implicated in generating symptoms in postinfectious and postinflammatory states in humans. Here we compared mechanisms of colonic afferent activation by 5‐HT and mechanical stimuli in normal and inflamed rat colon, and after recovery from inflammation. Colonic inflammation was induced in rats by dextran sulphate sodium. Single‐fibre recordings of colonic lumbar splanchnic afferents revealed that 58% of endings responded to 5‐HT (10⁻⁴m) in controls, 88% in acute inflammation (P < 0.05) and 75% after 21 days recovery (P < 0.05 versus control). Maximal responses to 5‐HT were also larger, and the estimated EC₅₀ was reduced from 3.2 × 10⁻⁶ to 8 × 10⁻⁷m in acute inflammation and recovered to 2 × 10⁻⁶m after recovery. Responsiveness to mechanical stimulation was unaffected. 5‐HT₃ receptor …