Protein and peptides production through recombinant techniques has benefited from numerous years of successful research, and is widely accepted as the approach of choice. As a result of these advances, many peptides and proteins are being formulated as biopharmaceuticals; however, to develop these macromolecules into stable formulations still remains a great challenge. Formulation problems in solution arise from the complex native structure of these macromolecules and are often manifested as physical instability, e.g. unfolding, aggregation, and/or precipitation. Understanding these effects is fundamental for research, development, production, and quality control. A variety of different techniques including HPLC, SEC, native gel electrophoresis and other electrophoretic techniques, analytical ultracentrifugation, fluorescence spectroscopy, Fourier transform/IR spectroscopy, mass spectrometry, light scattering, membrane osmometry, and UV spectroscopy have been used to study these processes. The assessment of product quality i.e. identity, content and purity has a major role in the manufacturing process of biopharmaceuticals. The biotechnological production process itself usually shows high variability, which introduces high product diversity. Even from production batches, only limited amounts of material may finally be approved for use and made available, requiring sensitive analytical technology. The purpose of the current review is to describe and discuss the latest advances in analytical methodologies used to secure final product quality.