Ten isolates of Potato virus Y (PVY) were collected from diseased potatoes grown at different locations in Egypt and some of their biological and molecular characters were studied using several techniques. Many different symptotypes were appeared on Chenopodium amaranticolar. Ch quinoa. Datura metal and Nicotiana tabacum cvs. Samsun and White Barley as a result of mechanical inoculation. All isolates reacted positively with monoclonal antibody specific to Potato virus Y group N. Reverse transcription-polymerase chain reaction (RT-PCR). hemi-nested and nested-RT-PCR were used to study their molecular characters. Three pairs of primers were selected to react with 5'-non-translation region (5'-NTR) and PI gene from the PVY genome. PCR products yielded by one primers pair reached 835 bp. while reached about 1 kb (974, 926 bp) by the other primers. Partial sequencing or fragment 835 bp was performed. Comparing with standard PVY strains showed highest similarity with PVY NTN -H followed by PVY NTN-Tu660, PVYN-Jg. PVY Wi and PVYN-Fre in rate of 98.8, 90.0, 89.9, 83.9, and 70.1 % respectively using DNASTAR software.