Pediculosis and scabies are caused by ectoparasites. Pruritus is the most common presenting symptom. Head and pubic lice infestations are diagnosed by visualization of live lice. Finding nits (louse egg shells) alone indicates a historical infestation. A "no nit" policy for schools and day care centers no longer is recommended because nits can persist after successful treatment with no risk of transmission. First-line pharmacologic treatment of pediculosis is permethrin 1% lotion or shampoo. Multiple novel treatments have shown limited evidence of effectiveness superior to permethrin. Wet combing is an effective nonpharmacologic treatment option. Finding pubic lice should prompt an evaluation for other sexually transmitted infections. Body lice infestation should be suspected when a patient with poor hygiene presents with pruritus. Washing affected clothing and bedding is essential if lice infestation is found, but no other environmental decontamination is necessary. Scabies in adults is recognized as a pruritic, papular rash with excoriations in a typical distribution pattern. In infants, children, and immunocompromised adults, the rash also can be vesicular, pustular, or nodular. First-line treatment of scabies is topical permethrin 5% cream. Clothing and bedding of persons with scabies should be washed in hot water and dried in a hot dryer.