Following passage of California Senate Bill No. 899 (SB 899) in 2005, disability in California is rated using the AMA Guides to the Evaluation of Permanent Impairment, (AMA Guides), Fifth Edition. The authors compare the disability ratings under the new law to those under the pre-2005 California Permanent Disability Rating Schedule. The authors reviewed 267 cases, of which 250 were ratable, and the ratings of expert reviewers who used the AMA Guides were compared with the ratings of the pre-2005 evaluations (the reviewers who used the AMA Guides to examine the earlier evaluations were blinded to the results of the earlier evaluations). The average permanent disability ratings were 22% under the old schedule and 6.4% under the new schedule, possibly because the current AMA Guides bases impairment primarily on objective data, not subjective complaints and opinions regarding work restrictions. The AMA Guides also has changed certain tests and minimized others (eg, range of motion and grip, respectively). Study limitations include sample selection and differences between pre-2005 evaluators and the highly proficient experts who used the AMA Guides for the present study. The authors conclude that this study shows ratings that are lower than those typically given by treating physicians and other examiners, and they note potential causes of the discrepancies, including evaluation by physicians who are not yet expert and experienced in using the AMA Guides.