Introduction. The prevalence of musculoskeletal disorders (MSDs) and non-communicable diseases (NCDs) increases with age. Purpose. The study examined the impact of MSDs and NCDs on work ability, using the Work Ability Index (WAI), among aging office workers (between 45-60 years old) and determined factors associated with WAI scores. Methods. A cross-sectional study was conducted in office workers from 27 government offices in Bangkok and nearby provinces using an online questionnaire. Analyses were conducted using Mann-Whitney U test and multivariable logistic regression model. Results. Of 689 workers (452 females and 237 males), 34%, 13%, 12%, and 41% reported MSDs, NCDs, MSDs + NCDs, and no MSDs/NCDs, respectively, in the past year. Median scores (interquartile range) of WAI were 37.0 (6) for MSDs, 37.0 (4) for NCDs, 34.5 (6) for MSDs + NCDs, and 40.0 (4) for no MSDs/NCDs. Significant difference in WAI scores was found between the MSDs and MSDs + NCDs (p = 0.005); and between the NCDs and MSDs + NCDs (p