Almost £1.3m in expenses and allowances was claimed last year by peers who failed to speak a single time in the chamber of the House of Lords, according to new research.
And 30 peers claimed more than £750,000 between them over the course of the last Parliament, from 2010 to 2015, without speaking once over the five-year period.
The chief executive of the Electoral Reform Society, Katie Ghose, denounced the figures as a "national scandal" which strengthened the case for reform of Parliament's upper house.
She called on Prime Minister David Cameron - who last month announced 45 new peers, bringing the total to over 800 - to take action to deliver a democratic second chamber
The ERS found £1,262,670 was claimed in expenses and allowances last year by peers who did not speak. Some 55 of those who failed to speak in the last session also voted fewer than five times, but claimed £92,075 between them.