In an effort to scientifically appraise the mechanism of action of Psdium guajava stem bark and leaves, the present study was carried out to investigate the cell membrane stabilizing anti-inflammatory activities of methanol extracts of psidum guajava on experimental animal model at three different dose levels – 5mg/kg, 10mg/kg and 15mg/kg. Aspirin (10mg/kg) was used as standard reference cell membrane stabilizing agent for comparison. This research work was carried out using Wistar strain albino rats weighing 150g-175g. The extractive inhibited heat- induced haemolysis of erythrocytes in vitro. The methanol extract of Psidum guajava stem- bark demonstrated 89.23%, 93.94% and 103.66% inhibition while the leave extract demonstrated 51.40%, 51.43%, 61.40% and 44.29% of hemolysis of RBC caused by heat, in a dose- dependent manner – 5mg/kg, 10mg/kg and 15mg/kg respectively. Results were considered significant at p ≤0.05.