The formulation PAA-ethanol, consisting of 0.2% paracetic acid (PAA) and 80% ethanol, nas tested for its virucidal activity on the enveloped vaccinia virus and papova virus SV 40 and the non-em eloped adenovirus type 2 and poliovirus type I. All test viruses were inactivated by PAA-ethanol within an exposure time of 1 minute, as measured by a log(10) reduction of + in virus titres. It was shown that poliovirus type I can be inactivated by PAA-ethanol within 1 min, whilst for the aqueous 0.2% PAA solution, an exposure time of 5 min is necessary. As shown by electron microscopic observation, the structure of virus particles was completely destroyed by 0.2% PAA within 15 min. The broad antimicrobial spectrum including a high virucidal activity, short exposure time and no toxic or allergenic decomposition products are favourable prerequisites for the medical use of PAA-ethanol and it warrants further investigation as a hand disinfectant, (C) 2000 The Hospital Infection Society.