Different preparations of human rhinovirus serotype 2 (HRV2), a common cold virus, were analyzed by capillary zone electrophoresis (CZE) in untreated fused-silica capillaries using borate buffer (100 mmol/L, pH 8.3) and sodium dodecyl sulfate (10 mmol/L) as additive to prevent wall adsorption. The electropherograms showed one major peak at 205- and 254-nm detection wavelengths. The identity of the peak as originating from native virus was confirmed by several indirect methods. Heating to 56 degrees C is known to lead to release of the genomic RNA from the viral capsid; this treatment resulted in the disappearance of the major peak and the emergence of a new predominant peak that was identified as RNA by enzymatic digestion. As expected, RNase treatment of the unheated sample remained without effect as the viral genome is inaccessible in the native viral shell. A monoclonal, virus-aggregating antibody was used for immunodepletion of native virus; again, the major peak disappeared upon removal of viral aggregates by centrifugation prior to CZE analysis. In combination, these results allowed for the unambiguous identification of the main peak as native HRV2 and of the minor peaks as contaminants present in various amounts in the different viral preparations. It is demonstrated that CZE allows for an extremely easy and rapid assessment of conformational state and purity of virions in a given viral preparation.