Polyamide manufacturing waste is often mechanically grinded and reinjected for economic and environmental purposes. However, the presence of humidity and impurities can cause significant damage leading to a loss of properties. Thanks to expertise carried out as part of this study, manufacturing defects linked to hygroscopicity are among the essential causes of production rejects. Thus, the study of the role and necessity of drying, as an intermediate step for the material preparation before injection, is gaining importance. Mechanical and thermal characterization is conducted on dried and undried samples of virgin and recycled polyamide 6 (PA6) and polyamide 66 (PA66). Recycling further promotes water absorption capacity, manifested in higher humidity levels. This introduces further variations in properties observed in recycled PA compared to its virgin state. Results show that the melting and crystallization temperatures remained stable across different conditions and materials, while the crystallinity content varied slightly with undried samples showing a little higher values. Moisture can increase the flexibility of polyamide chains, resulting in modifications in their mechanical characteristics. A notable outcome of this moisture absorption is a decrease in the material's strength and stiffness and an increase in elongation at break. Injection molding simulations are performed to assess the impact of PA6 humidity on the process parameters. Lower end of the filling phase temperatures and pressures and the end of cooling temperatures outcome under humid conditions relative to their dry state, indicating potential differences in material flow behavior and viscosity.