Objective: Characterize the prevalence of symptoms of musculoskeletal disorders in workers in micro and small-sized enterprises, exploring the types of exposure and ergonomic conditions, to propose improvements. Methodology: An exploratory descriptive cross-sectional descriptive study was carried out in 15 companies in Copiapó, Chile, with 119 workers (58 women and 61 men). The ergonomic analysis was carried out by means of open observations during the workday. Instruments according to Chilean standards and a survey to assess musculoskeletal symptoms and the nasa-tlx mental workload index were used to identify and assess MSD risk. Results: Women reported more symptoms of pain in the neck (46.6%), shoulders (58.6%), hands/wrists (51.7%) and hips (17.2%) than men, who reported more low back pain (52.5%). Repetitive work affected 83.2% of the workers, with 70.6% exposed to a high level of risk. Sixty-three percent faced risks due to manual handling of loads. As for mental workload, 30.3% experienced a high level, 40.3% a medium level and 29.4% a low level, with no significant differences between sexes. Conclusions: A high prevalence of WMSDs was observed among workers, related to high levels of mental workload in repetitive tasks and manual handling of loads. These conditions reflect labor precariousness and the influence of the gender division of labor. There is an urgent need to implement ergonomic interventions in MSMEs, but they face limitations due to informal work, the lack of visibility for preventive services and the lack of public health policies aimed at these populations. © 2024 Universidad de Antioquia. All rights reserved.