This study aimed to compare nutrient digestibility, preference rate, effects on stool and cost of grain-inclusive and grain-free dry dog foods. Two dry dog foods with and without grain formulated with poultry meal, barley, rice, corn, peas, carrot, potato flour, whey, fat, vitamin and mineral sources were manufactured. Twelve adult Golden Retriever dogs (age 3-4 years, body weight = 22.5±1.7 kg) were divided into two groups for the digestibility trial. A total of 20 Golden Retriever and Kangal (age 4-5 years, body weight = 35.5±1.9 kg) breed dogs were used for a two-pan preference test. Crude fibre digestibility of grain-free food was significantly lower (P<0.05). There was no difference in other nutrient digestibility in foods as determined by total faecal collection method. Presence of grains in food improved the consistency and dry matter of stool(P<0.05). Dogs preferred grain-free food (55.88%) to grain-inclusive food (44.12%) (P<0.05). The manufacturing cost of grain-free food was found to be about three times higher than grain food. The benefits of grain-free dog diets are debated. The effects of grain and grain-free foods on digestibility, stool parameters and canine health should be demonstrated by further studies. Cost must be calculated to produce reliable and suitable quality dog food with different ingredients. Palatability and intake levels, which are among the most important criteria in dog nutrition, should be determined by preference tests.