The Commons Health Select Committee heard evidence from experts in its first evidence session on its investigation into patient safety.
The NPSA runs a system where all NHS staff can report incidents or near misses so patterns can be spotted and the wider health community warned.
Incidents can include drugs administered in the wrong way or the wrong dose, medicines mixed up, the wrong operation carried out, a patient wrongly identified and broken or malfunctioning equipment.
Howard Stoate, a practising GP and Labour MP for Dartford, said the National Patient Safety Agency's own estimates suggest there are 72,000 preventable deaths in the NHS each year.
However, the incident recording database had collected just 3,200 reports of patient deaths, in 2007/8.
He said: "That is not just under-reporting, that is an extra-ordinary figure.
"If the public realised that only between five and ten per cent of preventable deaths are being reported they would have something to say about that.