This paper describes the measured long-term BTI field data from IBM zEnterprise EC12 systems in 32nm High-k/Metal Gate (HKMG) technology using a built-in monitor which is capable of separating the PBTI and the NBTI effects. The BTI monitor is accompanied by a digital thermal sensor in close proximity to correlate the BTI degradation with temperature. Comparable PBTI and NBTI degradation in use condition were observed. Compared with previous z196 microprocessor with 45nm SiON CMOS technology, the new 32nm zEC12 showed more than 2X less BTI degradation. This is attributed to HKMG technology optimization and lower chip voltages.