The genus Helichrysum (Asteraceae) is comprised of approximately 500-600 species and used for the treatment of a variety of pathological conditions in folk medicine in many countries. In this study, antioxidant activities of aerial parts of H. pseudoplicatum were investigated employing various in vitro assay systems, i.e. 2,2-diphenyl-1-picrylhydrazyl (DPPH)  and nitric oxide radical scavenging, reducing power and hydrogen peroxide scavenging. IC₅₀ for DPPH radical-scavenging activity was 438.9 ± 15.6 µg/ml. The extract exhibited good reducing power at 25 - 400 µg/ml but was not comparable with that of vitamin C. The extract showed good nitric oxide-scavenging activity. IC50 was 474.3 ± 11.8 µg/ml. It was capable of scavenging hydrogen peroxide in a concentration dependent manner. It showed good activity. Its IC50 was 159.8 ± 8.2 µg/ml. The IC50 values for ascorbic acid and BHA were 21.4 and 52.0 µg/ml, respectively. The total amount of phenolic compounds in the extract was determined as gallic acid equivalents (22.7 ± 3.1 mg/g of extract) and total flavonoid contents were calculated as quercetin equivalents (9.6 ± 1.3 mg/g of extract) from a calibration curve. This plant contained low amount of total flavonoids and phenolic compounds. Its moderate antioxidant activities may be attributed to its low levels of phenols and flavonoids.