Twenty-eight white-throated woodrats (Neotoma albigula) collected in Pima C
ounty, Arizona were screened for Leishmania using culture and the polymeras
e chain reaction (PCR). Two rodents were culture positive. Isoenzyme analys
is determined the isolates to be Leishmania mexicana. The two culture-posit
ive and four additional rodents were determined to be Leishmania-positive b
y the PCR. These isolates extend the geographic and ecologic range of enzoo
tic leishmaniasis in the United States and represent a new host record.