The Persian walnut (Juglans regia L.) is the most important shell fruit species in Hungary. Growing of this species became very popular in the past 10-15 years. Pomological evaluation of a double selected walnut population was done to select new promising genotypes at the National Agricultural Research and Innovation Centre – Fruitculture Research Institute. The experimental orchard was established in 1997, and it contains around 100 double selected different genotypes. The examined genotypes originated from the following combinations: ’Milotai 10’ x ’Pedro’, ’Pedro’ x ’Alsószentiváni 117’, ’Alsószentiváni 117 x Pedro’. During the examination period the most important characteristics of the genotypes were examined, such as leafing-out time, blooming time, ripening time and physical parameters of the walnut fruits. Based on our results five genotypes had late leafing-out time. Significant difference was observed during the examination of blooming time and ripening time compared to the standard Hungarian variety. Based on the results of the measurement of physical parameters all genotypes reached 32 mm fruit size in diameter, which is the requirement of the first grade fruits on the market. The fruit weight and fruit volume values of most hybrids exceeded the results of the control variety ’Alsószentiváni 117’. Only two genotypes reached 50% in kernel rate. 11 genotypes reached the ideal 70% cracking ratio (ratio of halves and whole). Based on the results of this study three genotypes (tree no. V/2/28-30, tree no. V/3/30-31 and tree no. BD6) were found which had excellent values. Further studies are required to investigate this three promising walnut hybrids. As these genotypes characteristics analyses carried out, also the compositional data of the walnuts was started to determine in the National Agricultural Research and Innovation Centre – Food Science Research Institute. Nuts and particularly walnut are recommended, important parts of human daily diet, because of their advantageous composition and nutritional value. Walnut is a good source of edible oil, fatty acids, tocopherols (vitamin E), phenolic compounds, and minerals (calcium, iron, magnesium, potassium). The composition of walnut (fatty acids, vitamin E, protein content) is affected by the cultivars, geographical origin, climate, storage. Walnut is a good source of oil (50-73 g/100 g) and rich in polyunsaturated fatty acids (PUFA). According to the composition of fatty acids walnut consumption has protective effect against cardiovascular diseases. The major fatty acids found in walnut oil are oleic acid (16-31 g/100 g), linoleic acid (50-63 g/100 g) and linolenic acid (8-14g/100 g). Gamma-tocopherol (164-295 mg/kg) is in ten times higher concentration than alfa- (8-21 mg/kg), and delta tocopherol (9-16 mg/kg), and tocopherols show antioxidant activity. Alfa-tocopherols presents the highest biological potential. Besides tocopherols the phenolic compounds (total polyphenols 1326-2175 mg/100 g) also have important role in protection against lipid oxidation. The research was supported by National Research, Development and Innovation Office in the frame of “Walnut breeding in order to release new late leafing and lateral bearing cultivar(s) project (project no. 123311).