The study endeavored to validate the antitussive activity of Trompang Elepante (Heliotropium indicum Linn.) leaf extract. It contains alkaloidal principle, specifically heliotrine, a pyrrolizidine alkaloid that inhibits the cough reflex by the inhibition of acetylcholine to bind at M3 receptors, thus smooth muscle contraction is suppressed. The study shows that Trompang elepante leaf extract does not contain toxic substances and free for further exploration of therapeutic effect based from the result of the Acute Oral Toxicity Testing. In the determination of Approximate Effective Dose, ten healthy Guinea pigs (5 males and 5 females) previously weighed and acclimatized inside the cough chamber was used in the experimentation. After acclimatizing, the guinea pigs were exposed to citric acid by enclosing the animals in cough chamber, nebulized to saturation with citric acid for them to inhale for 5 minutes. The number of coughs within 10 minutes was recorded. After recording the number of cough of each male and female guinea pigs, test animals received orally the determined dose in mg/kg body weight of Trompang elepante (Heliotropium indicum) leaf extract and then increased the dose logarithmically by 0.6 intervals (Bernas, 2004). After administration it was enclosed again in cough chamber and the number of coughs for 10 minutes was recorded. The results showed that the cough induction of citric acid was inhibited after the administration of Trompang Elepante leaf extract. From the experimental results, the Approximate Effective Dose is found to be between 158.49 to 2511.90 mg/kg dose level.