The apolar constituents of four Dianthus (Caryophyllaceae) species were determined by GC-MS. Palmitic, linoleic, and oleic acids were detected as dominant components in all species. D. elegans d′Urv. var. elegans had the highest antioxidant activity. All four species also showed considerable antimicrobial activity against S. epidermidis and C. albicans. Dianthus L. (Caryophyllaceae) is a genus of about 300 species in the world, distributed in the Mediterranean Region and in the Middle East [1]. In Turkey, 67 species are present, especially in Western Anatolia. Some Dianthus species are used in traditional medicine in addition to agricultural purposes [2-4]. According to the literature, they have antimicrobial [2], antihepatotoxic [4], analgesic [4], diuretic [5], and dermatologic [3] importance. The chemical constituents of this genus have generally been reported as triterpenoid saponins [4, 6], hydropyranes [7], and cyclic peptides [5]. Some GC-MS and LC-MS studies have determined that this genus consists of different types of terpenes [8], essential fatty acids [9, 10], and volatile compounds [11].In this study, we have determined the fatty acid components of the hexane extracts by GC-MS and investigated the antioxidant (by the DPPH method) and antimicrobial (by microdilution assay) activities of four Dianthus species, three of which are endemic to Turkey, for the first time.In this study, the apolar constituents of four Dianthus species were investigated using GC-MS for the first time. According to our results, the hexane extract yields were between 2.62% and 4.96% based on dry weight of the plant materials (Table 1). The highest percentage was detected in D. erinaceus var. erinaceus (4.96%). The total fatty acid components of hexane extracts varied from 95.23% to 98.48% (Table 2). The remainder of these percentages consisted mainly of phytol, eicosanol, and eicosane. The unsaturated fatty acid contents were higher than saturated ones, whereas some of the fatty acids were not observed in all species. In fact, all species contained unsaturated fatty acids, with a clear predominance of linoleic (LA) and oleic acids. One of the essential fatty acids (EFAs), LA, was a major component in all species, especially in D. elegans var. elegans with a component value of 51.98%. The other important essential fatty acid was present in the ratio 20:0, which was detected only in D. erinaceus var. erinaceus at 2.07%. Oleic acid was detected at high levels in all species as another unsaturated fatty acid. The highest oleic acid content was found in D. lydus at 48.54%. Palmitoleic acid was found only in D. lydus at 4.11%. In addition to these findings, myristic, palmitic, and stearic acids were found in all plants at more than 14.0% as saturated fatty acids.