The purpose of this study has been to identify the most common errors made by examiners during administration and scoring of the WISC-III. Five hundred test protocols from previous researches were analyzed. The results showed an average of 5.11 errors per protocols, while the larger percentage of errors has been verified in the scoring. During administration, the most common error was Failure to Query responses. Regarding subtests, the largest number of errors of administration and scoring was observed in Vocabulary (29.19%), Comprehension (25.9%) and Similarities (17.78%), thus corroborating literary findings, which suggest out these as the hardest subtests to score.