The behaviour of Escherichia coli O157:H7 during the storage of plain Ayran which was produced with mint (Mentha spicata), thyme (Thymus vulgaris), garlic (Allium sativum), salt (NaCl) and their mixture was investigated. Viability of E coli O157:H7 and the yoghurt bacteria Lactobacillus delbrueckii ssp. bulgaricus (LB) and Streptococcus thermophilus (ST) were studied in Ayran made with different spices. Ayran samples were produced in two different pH (4.4 and 4.6) values, and then the samples were stored at 4 degrees C for 21 days. During the storage period, viable counts of E coli O157:H7 fall was sharp from 6.40 to 3.10 (log cfu/g) at pH 4.4 and from 6.30 to 3.10 (log cfu/g) at pH 4.6. Additionally, E. coli O157:117 was not present at the end of 14th day of the storage. The inhibitory effects of spiced Ayran on E coli O157:H7 were similar to the control samples, without spice. The counts of LB and ST counts were approximately 4-5 log cfu/g at the end of storage. (c) 2005 Elsevier Ltd. All rights reserved.