Hypertension is one of the most common chronic diseases. Inhibitory activity of angiotensin I-converting enzyme (ACE) is effective on giving hypotensive effect. Jamfruit leaf (Muntingia calabura L.) was reported to have excellent hypotensive effect. This research was aimed to test in manner of in vitro the inhibitory activity of ACE using ACE kit-WST, total phenolic content, and total flavonoid from jamfruit leaves ethanol extract. The result showed that Jamfruit leaf extract had ACE inhibitory activity. IC₅₀ value of the ethanol extract against ACE was 1.25 µg/mL. Total flavonoid and phenolic content of the extract were 47.79 mg/g QE and 205.97 mg/g GAE. Ethanol extract of jamfruit leaves had ACE inhibitory activity, phenolic and flavonoid content which considered significant.