INTRODUCTION Questionnaires that measure functional status such as the Disability of the Arm, Shoulder and Hand (QuickDASH) and the Medical Outcomes Study 12-item Short-Form Health Survey (SF-12) can quantify the impact of health on performance. Little is known about whether these questionnaires can be used as a tool for measuring disabilities among workers. We compare the responsiveness of these two functional status questionnaires to changes in clinical outcomes of neck or upper extremity musculoskeletal disorders (UEMSD) among active workers in a longitudinal study. METHODS We evaluated the effect size (ES) and standardized response means (SRM) of the QuickDASH and the SF-12 for 148 workers who were divided into four subgroups based on the diagnosis status change between baseline and 1-year visit. RESULTS The ES and SRM for QuickDASH scores were 0.6/0.6 for the 50 subjects who became incident symptomatic neck or UEMSD cases, 1.3/1.0 for the 18 subjects who became incident clinical cases of neck or UEMSD, -1.0/-1.1 for the 46 subjects who recovered from having neck or UEMSD symptoms, and -1.1/-1.1 for the 34 subjects who recovered from being neck or UEMSD clinical cases. The correspondent ES/SRM for the QuickDASH work module were 0.4/0.3, 0.7/0.5, -0.6/-0.4, and -1.0/-0.8, respectively. The correspondent ES/SRM for the physical component scores of SF-12 (PCS12) for the four subgroups were 0.2/0.2, -0.9/-0.6, 0.3/0.2, and 0.3/0.3, respectively. CONCLUSIONS The QuickDASH scores were responsive to changes among active workers who were neck or UEMSD symptomatic or clinical case. PCS12 scores were sufficient only for use in clinical case status change.