Because of the recent fires in the western US interest has increased in the influence fire has on soil temperatures and plant root and microbial activity. There has been a long history of in situ soil temperature measurements during fires, but there are virtually no data available on soil heat flux during a fire. In this presentation we describe an experiment in which soil temperature and heat flux are measured during controlled burn of a Ponderosa Pine forest understory at the Manitou Experimental Forest in southern Colorado, USA during November 2001. Two separate sites where instrumented with 3 soil surface treatments at each site. The first site was heavily wooded and the soil surface was left unamended (i.e., it was covered with a light layer of needles). The second site was amended by adding fuel in the form a few (previously fallen) branches and the third was similar to the second only more heavily amended. The second site was in a small grassy opening. As with the forested site 3 amendments (low, medium, and high fuels) were applied. At each of the 6 treated sites soil temperatures were measured at 2,5,10,15, and 30 cm and soil heat flux was measured at 2, 10, and 30 cm. During the burn all data were recorded at 15 s intervals with datalogers displaced several feet from the fires. For protection from the fire all wires were buried in a 25 cm deep trench that had been backfilled with dirt. Results of the experiment indicate significant variation in the duration and magnitude of the temperature and heat flux pulses.