The American Society of Anesthesiologists (ASA) Physical Status Classification was tested for consistency among 304 anesthesiologists. A questionnaire was sent to them, asking to classify ten hypothetical patients. Of the 255 who responded, the average number of patients rated consistently was 5.9. Four patients elicited wide ranges of responses, with age, obesity, previous myocardial infarction, and anemia being sources of controversy. There was no significant difference in responses between regions of the country. Academic anesthesiologists rated more patients consistently than those in private practice. There was no difference in ratings between those who used the classification for billing and those who did not. The ASA classification is useful but lacks scientific precision. The ASA classification was originally designed to standardize physical status categories for statistical studies and hospital records. It was first proposed in 1940 by a committee of the American Society of Anesthetists. The classification was later revised in 1961 by Dripps et al. The system has not been tested for consistency among anesthesiologists. This study aimed to explore whether most anesthesiologists would rate the same patient in the same class, and whether ratings varied based on the anesthesiologist's background or practice. The study involved sending brief descriptions of ten hypothetical patients to 304 anesthesiologists. The responses were analyzed using statistical methods. The results showed that most anesthesiologists rated patients consistently, with a mean of 5.9 patients rated identically. However, four patients elicited wide ranges of responses, indicating controversy. The study found that academic anesthesiologists rated more patients consistently than those in private practice. There was no significant difference in ratings between those who used the classification for billing and those who did not. The study also found that recent perusal of the categories enabled more consistent ratings. However, the classification system lacks scientific precision and is not always used to indicate anesthetic risk. The study highlights the need for further clarification and refinement of the classification system. The results suggest that while the ASA classification is useful, it is not always consistent among anesthesiologists, and further research is needed to improve its accuracy.The American Society of Anesthesiologists (ASA) Physical Status Classification was tested for consistency among 304 anesthesiologists. A questionnaire was sent to them, asking to classify ten hypothetical patients. Of the 255 who responded, the average number of patients rated consistently was 5.9. Four patients elicited wide ranges of responses, with age, obesity, previous myocardial infarction, and anemia being sources of controversy. There was no significant difference in responses between regions of the country. Academic anesthesiologists rated more patients consistently than those in private practice. There was no difference in ratings between those who used the classification for billing and those who did not. The ASA classification is useful but lacks scientific precision. The ASA classification was originally designed to standardize physical status categories for statistical studies and hospital records. It was first proposed in 1940 by a committee of the American Society of Anesthetists. The classification was later revised in 1961 by Dripps et al. The system has not been tested for consistency among anesthesiologists. This study aimed to explore whether most anesthesiologists would rate the same patient in the same class, and whether ratings varied based on the anesthesiologist's background or practice. The study involved sending brief descriptions of ten hypothetical patients to 304 anesthesiologists. The responses were analyzed using statistical methods. The results showed that most anesthesiologists rated patients consistently, with a mean of 5.9 patients rated identically. However, four patients elicited wide ranges of responses, indicating controversy. The study found that academic anesthesiologists rated more patients consistently than those in private practice. There was no significant difference in ratings between those who used the classification for billing and those who did not. The study also found that recent perusal of the categories enabled more consistent ratings. However, the classification system lacks scientific precision and is not always used to indicate anesthetic risk. The study highlights the need for further clarification and refinement of the classification system. The results suggest that while the ASA classification is useful, it is not always consistent among anesthesiologists, and further research is needed to improve its accuracy.