The compressed liquid densities of binary mixtures of 1-butanol and diethylene glycol dimethyl ether (diglyme) have been measured over the temperature range from (283 to 363) K and at pressures up to 100 MPa covering the whole mole fraction of x(1-butanol) = (0, 0.3116, 0.5469, 0.7308, 0.8787, 1). The measurements were carried out using a high-pressure vibrating tube densimeter with the combined expanded uncertainty (k = 2) of 0.6 kg.m(-3). The experimental data were correlated using the modified Tait equation with an absolute average percentage deviation lower than 0.015% for each composition of the mixtures.