This study was conducted to determine the most suitable sowing date for coriander (Coriandrumsativum L.) at the Harran Plain conditions. The study was carried out at the experiment area of Field Crops department, Agriculture Faculty, Harran University during 2001-2002 and 2002-2003 growing season. Field trail was arranged in randomized block design with three replications. In this study, total 14 sowing times, from beginning October hence between approximately 15 days,were tested. It was determined that plant height, number of umbel, seed number of main umbel,1000-seed weight, essential oil content, seed yield and essential oil yield were significantly changed depending on the sowing time.