To investigate the developmental pathways of multisite musculoskeletal pain (MSP) and the effect of physical and psychosocial working conditions on the development of MSP trajectories.The study was conducted among food industry workers (N=868) using a longitudinal design. Surveys were conducted every 2 years from 2003 to 2009. The questionnaire covered MSP, physical and psychosocial working conditions (physical strain, environmental factors, repetitive movements, awkward postures; mental strain, team support, leadership, possibility to influence) and work ability. MSP as an outcome was defined as the number of painful areas of the body on a scale of 0-4. Latent class growth modelling and multinomial logistic regression were used to analyse the impact of working conditions on MSP pathways.Five MSP trajectories (no MSP 35.6%, persistent MSP 28.8%, developing MSP 8.8%, increasing MSP 15.3% and decreasing MSP 11.5%) were identified. In a multivariable model, the no MSP pathway was set as the reference group. High physical strain (OR 3.26, 95% CI 2.10 to 5.04), poor environmental factors (3.84, 2.48 to 5.94), high repetitive movements (3.68, 2.31 to 5.88) and high mental strain (3.87, 2.53 to 5.92) at baseline predicted the persistent MSP pathway, allowing for poor work ability (2.81, 1.84 to 4.28) and female gender (1.80, 1.14 to 2.83). High physical strain and female gender predicted the developing MSP pathway. High physical strain, poor environmental factors and high repetitive movements predicted the increasing and decreasing MSP pathways.A substantial proportion of individuals reported having persistent MSP, and one-third reported changing patterns of pain. Adverse physical working conditions and mental strain were strongly associated with having high but stable levels of MSP.