Introduction: The aim of this study was to determine the effects of gamat extract on pain behaviour and Fos like immunoreactivity (FLI) expression in the ventral posterolateral thalamus using the acute pain model. Materials & Methods: Fourteen Sprague-Dawley male rats (220-300 gram) were given intraplantar injection of 0.05ml formalin (1%) followed by intraperitoneal administration of either 4 mg/kg gamat extracts (Holothuria spp.) or saline (control). Behavioural changes were observed and rats were sacrificed 2 hours post-formalin injection. Immunohistochemistry testing was done on the brain sections. FLI was examined using a light microscope attached to an image analyser. The behaviour and FLI data were analysed using repeated measure analysis of variance and independent t-test respectively. Significance level was taken as p