The Denton County Health Department confirmed the second death of a patient who had contracted West Nile virus.
Health officials say the patient was a woman in her 80s and had underlying health conditions.
DCHD said the patient lived in Carrollton in zip code 75010.
Denton County declared a state of emergency on Wednesday because of the West Nile virus outbreak of West Nile in North Texas.
Cities have until Tuesday to decide to join in the county's aerial-spraying effort.
Denton County had 118 human cases of West Nile virus as of Thursday, more cases per capita than any other county.