Allelopathic effects of juglone and walnut leaf extracts from Persian walnut (Juglans regia L.) on yield, growth, chemical and plant nutrient element composition of the day-neutral strawberry (Fragaria x ananassa L.) cultivar Fern were investigated as part of an effort to identify tolerant species to plant adjacent to walnut. Strawberry plants were treated with juglone (5-hydroxy-1.4 naphthoquinone, 1mM) and walnut leaf extracts (undiluted, 1:2, 1:4, 1:8 diluted). Vegetative and reproductive plant growth was inhibited strongly by the treatment of both juglone and undiluted walnut leaf extracts. Fruit yield per plant, the number of fruit per plant, average fruit weight, crowns per plant, number of leaves, leaf area, fresh root weight, total soluble solid (TSS), vitamin C and acidity were reduced by juglone treatment compared to the control. All nutrient elements analyzed in the leaves generally were lower than the control for all treatments except 1:8 diluted.