Corrosion inhibition effect of alkaloid extract part of the plant Trichodesma indicum (Linn) R. Br. of Boraginaceae family was studied and compared with that of imidazole compounds (imidazole, benzimidazole) on C38 steel in 1 M HCl solution by weight loss method at various temperatures. The study showed that the alkaloid part of the plant extract acts as a better inhibitor in comparison to the selected organic inhibitors. The maximum inhibition efficiency of the extract of Trichodesma indicum R. Br. was found to be 94.5% at a concentration of 75 mg/L at 30°C.