In this proceedings I summarize results of QCD trace anomaly from recent three-loop hard-thermal-loop perturbation theory (HTLpt) calculations. I focus on the trace anomaly scaled by T
2 for pure-glue and N
f = 3 QCD. The comparison to available lattice data suggests that for pure-glue QCD agreement between HTLpt results and lattice data for the trace anomaly begins at temperatures above 8 T
c while when including quarks (N
f = 3) agreement begins already at temperatures above 2 T
c. The results in both cases indicate that at very high temperatures the T
2-scaled trace anomaly increases with temperature in accordance with the predictions of HTLpt.