Antimicrobial activity from soursop leaves extract was observed in this study. The aim of this research was to determine antimicrobial capacity of soursop leaves extract in inhibiting pathogenic microorganisms. Soursop leaves were macerated with ethanol for 72 hours in room temperature. The result showed that extract could inhibit growth of S.aureus (8,48-12,64mm), B.cereus (6,28-12,28mm), S.Typhi (3,26-8,91mm) and P.aeruginosa (4,24-9,76mm), but could not inhibit A.flavus. The most sensitive bacteria was S.aureus based on MIC and MBCvalues. The active compounds in ethanolic extract of soursop leaves are tannin, flavonoid, alkaloid, saponin, phenolic compounds, steroid, and glycoside. Extract of soursop leaveswere affected by time of heating (5,10,15 minutes). The extract showed stronger inhibition capability than penicillin G and streptomycin 10 ppm for bacteria. Leakage of cells were detected by AAS and supported by SEM. In addition a GC-MS study of some fractions revealed the presence of several compounds such as /3-sitosterol, vitamin E, ethyl ester, phytol, a-linolenic acid, hexadecanoic acid, andoleic acid. This extract is classified in the low level toxic (LC50= 201,07 ,ug/ml).