Fifty adult febrile patients, 25 men and 25 women, had six one-in minute rectal temperature readings taken in rooms ranging from 72 to 82 F. The Maximum and optimum rectal thermometer placement times for febrile adults were three and two minutes respectively. It was concluded that two minutes would adequately reflect adults rectal temperatures. This confirms the findings from previous studies and is less time than that recommended in some texts and procedure books.