In this study, some selected physico-chemical properties (antioxidant activity, ascorbic acid, fatty acids, fruit colour, fruit juice yield, fruit weight, organic acids, pH, total phenolic and total soluble solid contents) of five black mulberry (Morus nigra L.) genotypes grown in the Northeast Anatolia region of Turkey was investigated. The total phenolic and antioxidant activity of methanol extract of black mulberry fruits were determined according to Folin-Ciocalteu and beta-carotene bleaching method assays, respectively. Fatty acids of mulberry fruits were determined by using gas chromatography. Total phenolic content was observed in black mulberry fruits between 1943 and 2237 mg gallic acid equivalents/100 g fresh mass. The vitamin C content of genotypes varied between 14.9 and 18.7 mg/100 ml. The major fatty acids in all mulberry fruits were linoleic acid (53.57-64.41%) and palmitic acid (11.36-16.41%). Antioxidant activity of black mulberry genotypes was found between 63% and 76%, which lower than standard BHA and BHT. Regarding organic acid content, malic acid was the most predominant with a range of 123-218 mg/g followed by citric acid (21-41 mg/g). The results of the study are helpful for attempting crop improvement in black mulberry for bringing to cultivation. (c) 2007 Elsevier B.V. All rights reserved.