Abstract: Strains of Zucchini yellow mosaic virus (ZYMV) were obtained from different cucurbit crops in different parts of Iran such as Isfahan (Is), Mazandaran (Sh), Karaj (Kr), Varamin (Vr), Khorasan (Kho), Kerman (Jr), Khuzestan (Dez and Jaz), Hamedan (Amz), Saveh (Sa), Markazi (Mkh), with one seed borne strain from Hamedan (Sdh) were partially characterized and compared. Variability was detected among strains regarding symptomatology and host range. These strains were different and distinguishable in the ability to infect specific hosts and divided into three groups. In one group, there were strains of Mazandaran, Karaj and seed borne Hamedan strain. In the second group, there were those of Varamin, Khorasan, Kerman, Isfahan, Saveh and Markazi province and in the third group there were strains of Khuzestan. Reverse Transcription-Polymerase Chain Reaction (RT-PCR) of the NIb and N-terminal part of the coat protein coding region, followed by Restriction Fragment Length Polymorphism (RFLP) analysis of the PCR product of the thirteen mentioned strains with two restriction enzymes has been shown not to be an effective procedure for discriminating strains.