The surface heat budget for the absolutely dry soil of the Pampa de La Joya, Peru, a portion of the Atacama Desert, was determined for three round-the-clock periods in July 1964. The diurnal variations are described by the mean value and the amplitude and phase angle of the first three harmonics. The measurements include global insolation, net radiation, soil heat flux density, sensible heat flux density, surface temperature, and air temperature at 20, 40, 80, 160, and 320 cm. The instruments used are described, and an estimate of the errors in measurement is made for each.