In this study, the aqueous (AQJP) and alcoholic (ALJP) extracts of the whole plant of Justicia prostrata Gamble (Acanthaceae) were screened for their acute and subacute anti-inflammatory activities using carrageenan-induced acute inflammation and cotton-pellet-induced granuloma (subacute inflammation), respectively, in rats. In the carrageenan-induced rat paw oedema model, both extracts were found to exhibit maximum reduction in paw volume at the first hour in a dose-dependent manner. At the dose of 500 mg/kg p.o., both extracts AQJP and ALJP showed maximum inhibition (51.39% and 62.5%, respectively) in rat paw oedema volume at the first hour of carrageenan-induced acute inflammation. In the cotton pellet granuloma assay, AQJP and ALJP at the dose of 500 mg/kg p.o. suppressed the transudative, exudative and proliferative phases of chronic inflammation. These extracts were able to (i) reduce the lipid peroxide content of exudates and liver and (ii) normalize the increased activity of acid and alkaline phosphatases in serum and liver of cotton pellet granulomatous rats. Preliminary phytochemical screening revealed the presence of lignans, triterpenes and phenolic compounds in ALJP, whereas phenolic compounds and glycosides in AQJP. The anti-inflammatory properties of these extracts may possibly be due to the presence of phenolic compounds. The anti-inflammatory effects produced by the extracts at the dose of 500 mg/kg, p.o. was comparable with the reference drug diclofenac sodium (5 mg/kg p.o.).