A recent review has suggested that the commonly cited value of 1.45×1010 cm-3 for the silicon intrinsic carrier concentration at 300 K is inconsistent with the best experimental data. An alternate value of 1.08×1010 cm-3 was proposed. From measurements of the current-voltage characteristics of p-n junction diodes, this paper reports a new and more accurate determination of this parameter over the 275-375 K temperature range which supports such lower values. The one-standard-deviation uncertainty in the measurement of the intrinsic carrier concentration is estimated to lie in the 3%-4% range, about three times smaller than previous measurements at these temperatures. Additionally, this technique provides information on the minority carrier electron diffusivity in silicon.