Respirator fit testing is mandatory under current legislation. It is vital that selected respiratory protective equipment (RPE) is adequate and suitable for the purpose. The performance of tight fitting face pieces relies heavily on the quality of fit to the wearer's face - on achieving a good contract between the wearer's skin and the face seal of the face piece. An inadequate fit will significantly reduce the protection provided to the wearer. Any reduction in protection can endanger the wearer's life or lead to immediate or long-term ill health. Whilst fit testing has a key role to play, it must not be forgotten that this is only one small part of a respiratory protection programme. For adequate respiratory protection to be achieved in the workplace, a comprehensive and effective respiratory protection programme must be in place.