Abstract Twenty-six aged hardaliye samples, collected from different spots of the Kirklareli province of Turkey and hardaliye produced in laboratory conditions using the traditional method were investigated in this study. The pH ranged from 3·21 to 3·97. Red colour (Hunter Lab a Lvalue) of samples ranged from 1·33 to 9·66. The total bacterial count ranged from 3·5×10 2to 8×10 5cfu ml −1. The lactic acid bacteria counts of the samples were found to be between 1·0×10 2and 4·0×10 4cfu ml −1. Yeasts and moulds, which were found in 21 samples out of 26, ranged from 1·0×10 2to 8·1×10 4cfu ml −1. Coliforms and Escherichia coli were found in none of the samples. The changes of some microbiological and chemical properties of hardaliye during fermentation were investigated. The pH of hardaliye dropped from 3·86 to 3·39. The ethanol content of the end product was determined as 595·50 mg dl −1. During the fermentation process, the total bacteria count, lactic acid bacteria count and yeast count changed from 2·1×10 5, 6·0×10 4and 1·2×10 5cfu ml −1to 1·3×10 2, 1·2×10 3and 1·1×10 3cfu ml −1, respectively. Lactobacilli isolated from hardaliye samples were characterized by API 50 CH and other phenotypic criteria. A succession of Lactobacillus species, dominated by L. paracasei subsp. paracasei and L. casei subsp. pseudoplantarum were found during the fermentation process.