Scedosporium boydii and Lomentospora prolificans are filamentous fungi reported to cause infection in immunocompromized individuals. We studied the effect of farnesol to inhibit growth of S. boydii and L. prolificans by measuring colony diameter and determining minimal effective concentration (MEC). S. boydii and L. prolificans were grown on Sabouraud dextrose agar (SDA) at 37oC for 5 days. Conidia were collected and adjusted to a concentration of 104 conidia/ ml. Twenty microliters of conidia suspension was placed in each well of a sixwell plate containing serial dilutions of farnesol (10 μM, 100 μM, 1,000 μM, and 10,000 μM) in SDA. Colony morphology and diameter were observed on days 1, 2, 3, and 4. Farnesol at concentrations of 1,000 μM or higher caused the colony diameter of both S. boydii and L. prolificans to be smaller than untreated controls in a dose-dependent manner. The MEC of farnesol to inhibit growth of both S. boydii and L. prolificans was 3.2 mM. This study reveals the antifungal property of farnesol against S. boydii and L. prolificans, which can be used for further study as an alternative antifungal agent against these fungal infections.