Pediculosis and scabies are caused by ectoparasites; patients usually present with itching. Head and pubic lice infestations are diagnosed by the visualization of insects or viable nits (eggs). Primary treatment is topically administered 1 percent permethrin. Malathion is one alternative for treatment failures. The importance of environmental measures to prevent infestation is a matter of controversy. Pubic lice are treated the same as head lice, but this finding should prompt evaluation for other sexually transmitted diseases. Body lice infestation should be suspected when symptoms of generalized itching occur in persons who do not change or wash their clothing or bedding regularly; lice may be found in the seams of their clothing. Topically administered permethrin may help to eradicate body lice, but personal hygiene measures are essential for successful treatment. Classic scabies in adults can be recognized by a pruritic, papular rash with excoriations; in infants, small children, and the immunocompromised, the rash may include vesicles, pustules, or nodules. Primary treatment for scabies is permethrin cream and environmental measures are important to prevent recurrent infestation. Generalized crusted scabies is best treated with oral ivermectin.