There is a wide range of nematode species of zoonotic potential that can infect pet dogs. The present study was conducted to detect nematode infestation in pet dogs in Lahore. Two types of nematodes were identified (Toxocara canis and Ancylostoma caninum) in fecal samples of 300 pet dogs from January 2011 to June 2011 by various techniques . The prevalence of T.canis was 11.33% and 8.33% for A.caninum by Direct Smear Method. By Flotation Technique prevalence of T.canis was 14.33% and 12.3% for A.caninum and by Sedimentation Technique the prevalence of T.canis and A.caninum was 11.66% and 10% respectively. To investigate the effect of physical factors on prevalence of nematodes, month-wise mean temperature and mean monthly relative humidity was also analysed. The results of study revealed that temperature has a positive relationship with the prevalence of infection. But the percent prevalence of both types of nematodes did not show any direct relation with relative humidity.As pet dogs are the reservoir of transmission of diseases to humans specially children, so there is a need to control of nematode infections by establishing hygienic conditions and regular clinical examination