The relative importance or utility of the carbon dioxide laser within the total context of multimodality therapy and in comparison to conventional surgical techniques is unknown. Over a 36 month period, 421 operations for tumors of the brain and spinal cord were performed in our clinic. Of these, 111 (26%) were carried out with the aid of the laser. After excluding stereotactic and transsphenoidal operations, a comparison was made between 105 laser and 216 non-laser craniotomies. With the exception of pituitary tumors, the most frequent diagnoses in both the laser and non-laser cases were the same: malignant astrocytoma (48.6 vs 33.9%), meningioma (11.4 vs 14.2%) and low grade astrocytoma (8.6 vs 8.7%). The number of reoperations in the laser group (60.1%) was higher than in the non-laser group (32.7%; p less than 0.000001) and the mean operating time (299 minutes vs 237 minutes; p less than 0.00001) was longer, but there was no significant mean difference in mortality, CNS morbidity, mean blood loss (638 ml vs 671 ml) or mean length of stay (23 vs 25 days). For the subgroup of 134 cases of malignant astrocytoma, 82% of laser procedures were reoperations versus 50% for non-laser cases (p less than 0.0002) and the mean operating time was slightly longer (p less than 0.02). The length of stay for laser cases tended to be less (21 vs 27 days; p less than 0.04), but there was again no difference in blood loss (457 ml vs 522 ml), CNS morbidity (7.8 vs 4.8%) or mortality.(ABSTRACT TRUNCATED AT 250 WORDS)