The present study was conducted to investigate egg size of F.hepatica and F. gigantica among cattle, buffaloes and human. Lymnea cailliaudi infection potential with F.hepatica was also studied expermintally. Fasciola flukes were collected from slaughtered animals, eggs were teased from the uteri of the collected flukes and measured. Fasciola eggs were collected from stool of 51 human cases with chronic fascioliasis and measured microscopically using the micrometer. Eggs identified as F. hepatica were used for experimental snail infection. Results indicated the presence of egg size variations according to the animal species. Eggs of F.gigantica were significantly larger and broader than those of F. hepatica. A positive correlation between egg legnth and breadth was observed in case of F hepatica only. Human egg isolates were considered mainly F hepatica.