This work presents a 3D MR temperature imaging (MRTI) sequence for breast MRgFUS. A 3D gradient echo with segmented echo planar imaging readout sequence with time-varying drift correction was used in female volunteers and tissue-mimicking phantoms. Temperature changes due to FUS heating in phantoms were measured with fiberoptic probes and compared to MRTI. Non-heating volunteer data was also acquired. Temperature in the phantom studies was accurate compared to FO probes with an RMSE of 1.0°C. Mean precision and accuracy of 1.05 and 1.29°C were measured in healthy volunteers. This sequence provides accurate and precise 3D temperature measurements for breast MRgFUS.