Treatment with steam and/or dilute NaOH are commonly used techniques to disinfect manufacturing vessels and tools in the pharmaceutical industry. The aim of this procedure is sanitisation and inactivation of microbiological and viral contaminants. Here we describe the inactivation of the mouse parvovirus Minute Virus of Mice (MVM) under these conditions. Parvoviruses are known to be resistant to physico-chemical treatment and one representative of this family, the human parvovirus B19, is a potential contaminant of blood plasma. We show inactivation kinetics for MVM treated with wet-heat (70, 80, 90 degrees C) and with 0.01-1 M NaOH solutions (pH >/=11.9). Robust inactivation was only achieved at 90 degrees C for at least 10 min and in NaOH solutions of pH >/=12.8 (0.1 M NaOH). It was observed, that aggregation of viruses might protect viral particles from inactivation by NaOH. Therefore, appropriate sample preparation of spiking material is important for accurate simulation of the naturally occurring situation. The observed stability at pH 11.8 exceeds the previously reported upper limit of pH 9. Inactivation was due to disintegration of the viral capsid as assessed by accessibility of viral DNA for endonucleases.