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A novel injectable male contraceptive (RISUG®: an acronym for Reversible Inhibition of Sperm Under Guidance) has been developed by our research group and is currently in the advanced clinical trial stage. RISUG® consists of a copolymer styrene maleic anhydride dissolved in dimethyl sulfoxide of a particular formulation and is injected into the lumen of the vas deferens using a no-scalpel approach. Its polyelectrolytic nature induces a surface charge imbalance on the sperm membrane system leading to the leakage of enzymes essential for sperm-egg interaction. In the present study, surface characterization of the contraceptive using atomic force microscopy (AFM) is proposed. RISUG® gel was spin coated on glass sides and hydrolyzed with saline and seminal plasma to mimic in vivo conditions. Contact mode atomic force microscopy (AFM) has been used to analyze quantitatively the micro-structural properties of RISUG® and its precipitate in various systems. Hydrolysis of the contraceptive gel resulted in the formation of pores of varying dimensions. RISUG® being a highly charged molecule, as evident from zeta potential measurements, has a tendency to form a complex with ionic biomolecules present in the seminal plasma. This is supported by the experimental observations using AFM. This RISUG® - biomolecule complex possibly acts as an ionic trap for spermatozoa passing through the vas deferens. Micro-structural properties of RISUG® including amplitude (root mean square, peak-to-valley distance, skewness, and kurtosis) and spatial roughness have been studied to understand its response to various physiological conditions. [ABSTRACT FROM AUTHOR]