The Construction Research and Training Center states that lifting and lowering materials causes 30% of musculoskeletal disorders among construction workers. Then excessive activity coupled with pushing, pulling, holding, carrying, and catching materials can add 37% of musculoskeletal complaints. The purpose of this study was to determine the effect of age, length of service, body mass index, physical fitness, and smoking habits on complaints of musculoskeletal disorders through work posture in construction workers of the Makassar vertical hospital construction. This type of research uses mixed method research with a cross sectional approach. The quantitative sample of this study using proportionate random sampling amounted to 243 respondents and the qualitative sample amounted to 6 main informants and 2 key informants. The results of this study indicate that the variables of age (0.041) and body mass index (0.047) have a direct and indirect effect on musculoskeletal disorders through work posture. Whereas working period (0.126), physical fitness (0.581) and smoking habits (0.366) affect musculoskeletal disorders directly without going through work postures. Therefore, both workers and management must work together in implementing health programs or work rules to minimize the risk of musculoskeletal disorders in construction workers.