Phage therapy is re-established to treat antibiotic-resistant bacterial infections. Bacteriophages are natural predators of bacteria and the studies on therapeutic potential of phages are increasing in the recent times. The aim of this study is to use a simple live animal model, Caenorhabditis elegans to evaluate the treatment efficacy of bacteriophages. For this study, four clinical bacterial strains Escherichia coli 131, Escherichia coli 311, Klebsiella pneumoniae 235 and Enterobacter cloacae 140 and their bacteriophages were used. In a liquid-based assay, the bacteriophages were able to increase the lifespan of infected nematodes up to 7-fold. In the bacteria infected groups, the nematode survival was reduced to <20% within 80 hrs. The prophylactic treatment group had better efficacy than the therapeutic treatment group. During nematode scoring, no movement was observed after 96 hrs when the nematodes were not fed with E. coli OP50. This study using C. elegans, a simple whole-animal infection model to determine the therapeutic efficacy of bacteriophages is one of the first in this platform which can be explored further to study the efficiency of phage therapy.