In a trial to investigate the bacterial causes of leg infection in broiler chickens, a total of 308 samples (foot bad and hock joint) of broiler chickens suffering from lameness were collected randomly from different broiler farms at Ismailia, Sharkia and North Sinai Governorates. Clinical and post-mortem examination, besides bacteriological analysis of the samples were carried out. The bacteriological investigation revealed the isolation of Staphylococcus aureus (83.8%, 258/308), Staphylococcus lentus (16.2%, 50/308), Escherichia coli (28.6%, 88/308); Salmonella spp.(1.3%, 4/308), Pseudomonas aeruginosa (1.9%, 6/308)and Pasteurella multocida (1.9%, 6/308). Antimicrobial sensitivity tests of the isolated bacteria revealed that S. aureus isolates were sensitive to Cefotaxim, Ciprofloxacin, Enrofloxacin and sulpha Trimethoprim. Virulence associated factors (coagulase gene and clumping factor) were determined in S. aureus isolates by conventional PCR.  The results showed that the coagulase gene was identified in 10 S. aureus isolates, while, the clumping factor was detected in only two isolates. It could be concluded that the staphylococcal infection is the most important cause of arthritis in broiler chickens.