Late blight, caused by Phytophthora infestans (Mont.) de Bary, is a devastating disease found worldwide. During 2011, 2013 and 2014 cropping seasons, prevalence of potato late blight in all survived areas throughout the interior of Syria was examined and the disease incidence varied and ranged from 0 to 85.71%. Potato leave samples showing late blight symptoms were collected from five different regions known to grow potato intensively. Based on their morphological characteristics, 22 isolates were distinguished as P. infestans. Using two fungal specific primers, ITS3 and PINF2 in a PCR assay, all isolates were confirmed as P. infestans, while they produce ~ 450 bp band. Similarly, all confirmed P. infestans isolates were able to produce a 170-bp band when INF-1 and INF-2 primers were deployed indicating that studied isolates had merely mating type A1 and no isolate with mating type A2 was found which might explain the absence of oospores in considered areas