Homeless people in developed countries have specific problems predisposing them to infectious diseases. Respiratory infections and outbreaks of tuberculosis and other aerosol transmitted infections have been reported. Homeless intravenous drug users are at an increased risk of contracting HIV, and hepatitis B and C infections. Skin problems are the main reason the homeless seek medical attention, and these commonly include scabies, pediculosis, tinea infections, and impetigo. Many foot disorders are more prevalent in the homeless including ulcers, cellulitis, erysipelas, and gas gangrene. The louse transmitted bacteria Bartonella quintana has recently been found to cause clinical conditions in the homeless such as urban trench fever, bacillary angiomatosis, endocarditis, and chronic afebrile bacteraemia. Treatment of homeless people is complicated by financial constraints, self-neglect, and lack of adherence. Patients with serious and contagious illnesses should be hospitalised. Physicians should be aware of these specific issues to enhance care.