Forty five Streptomyces strains were isolated from the soil of Riyadh region at Saudi Arabia. All these strains were screened for an antifungal activity against some unicellular and filamentous fungi. The results proved that one strain was found to possess broad spectrum antifungal activity, thus purification and characterization of an antifungal agent were taken place. The concerned strain was identified as Streptomyces paradoxus, where the nucleotide sequence of 16S RNA gene (1.5 Kb) of this strain evidenced a 99% similarity with Streptomyces paradoxus. Moreover, there is high matching between the isolated strain and Streptomyces paradoxus in the morphological, physiological and biochemical characteristics. The antifungal metabolite was extracted using n-Butanol (1:1, v/v) at pH 7.0. The separation and purification of an antifungal agent were performed using both thin layer chromatography (TLC) and column chromatography (CC) techniques. The physico-chemical characteristics of the purified antifungal agent have been investigated. The collected data revealed that, the suggested empirical formula of antifungal agent is C₂₄H₁₉NO. The minimum inhibitory concentrations “MICs” of the purified antifungal agent were also determined. Eventually, the results emphasized the fact that the purified antifungal agent was suggestive of being belonging to 4′ phenyl-1-napthyl-phenyl acetamide antibiotic.