Passengers using Heathrow rose by 6.7% last month to 6.2 million due to the late Easter.
Underlying growth was 1.9% when taking into account the Easter timing change from 2013, the airport reported today.
Traffic to emerging markets saw travellers to China up 12.5%, Mexico up 15.9% and India up 9.2%.
Seats per aircraft increased 1.3% to 205.6, while load factors increased 4 percentage points to 78.3%. Passengers per aircraft increased 6.7% to 161.
Heathrow chief executive Colin Matthews said: “Our capital programme and continuous operational improvements have supported record customer satisfaction levels, with the proportion of passengers rating their journey as ‘very good’ or ‘excellent’ increasing from fewer than half six years ago, to a record high of 80% this quarter.
“With the brand new Terminal 2 set to open on 4 June, we hope to improve those scores further in 2014.”