A study was undertaken on two commercial feedlots located near Dalby, Queensland from 2 January to 31 March 2002. At each location four pens of long fed (250 days)Angus steers (150 to 200 head/pen)were used. Two of the pens had shade and two did not. On both sites the two shaded pens were located next to one another. The unshaded pens were also located next to each other. Weather stations were set up at each site. One station was located under the shade structure (shaded pens) and the other was located in an unshaded pen. Measurements taken included ambient temperature, black globe temperature relative humidity, solar radiation, wind speed and wind direction. Weather data was collected at 30 minute intervals. Cattle data collected included respiration rate, feed intake, location in pen (e.g. at water trough or feed bunk). The data was collected at hourly from 0600 to 1800 h on days when it was predicted that ambient temperature was likely to exceed 35 C. Cattle observations were also undertaken on "non stressful" days in order to establish a base line for respiration rate and behaviour. Preliminary data analysis has shown differences in cattle behaviour between hot days and non stressful days. Differences were also seen in regard to respiration rate between shaded and unshaded cattle on hot days.