Using an infrared radiation thermometer and a laser flare-cell meter, we evaluated intraocular inflammation in 40 patients who had cataract surgery by measuring central corneal temperature, number of cells, and amount of flare in the anterior chamber. Patients were divided into two groups based on duration of surgery: Group A, more than 40 minutes; Group B, less than 40 minutes. In Group A (n = 32), corneal temperature (degrees Celsius) increased by 1.10 +/- 0.57, 0.75 +/- 0.69, 0.41 +/- 0.56, and 0.24 +/- 0.45 on days 1, 2, 14, and 30, respectively. Group B (n = 8) had no significant rise in corneal temperature, but cell count (mean +/- 1 SD) increased to 39.3 +/- 13.6, 36.4 +/- 18.1, 15.5 +/- 16.5, and 4.4 +/- 3.1 on days 1, 2, 7, and 14, respectively. Flare increased to 88.9 +/- 88.9, 45.8 +/- 30.1, 38.3 +/- 25.4, and 18.5 +/- 9.4 on days 2, 7, 14, and 30, respectively. These observations show that the longer the cataract surgery, the greater the inflammation. Although inflammation was evaluated quantitatively by both infrared radiation thermometer and laser flare-cell meter, the latter appears to be more sensitive. Thermometry will only detect the results of very traumatic surgery, with a corresponding breakdown of the blood-aqueous barrier.