Heathrow saw 6.9 million passengers in July, a 5.5 per cent increase on July 2012.
The growth is largely attributable to lower traffic in July last year as a result of the timing of the London Olympics.
Load factors continued to be high at the same time as average aircraft size maintained its recent upward trend.
The average number of seats per aircraft was 203.5, up 2.9 per cent.
However, the average number of passengers on each flight rose five per cent to 168.5, pushing load factors to 82.8 per cent, up 1.7 percentage points on July 2012.
On a regional basis, East Asia traffic saw the biggest rise, up 18.9 per cent, largely as a result of increases in capacity.
Latin America was up by 5.9 per cent in total, with most of the growth coming from additional capacity on services to Mexico.
European traffic continued to see the effects of BA’s integration with BMI, up 8.9 per cent, including growth in Italy (21.1 per cent), France (17.4 per cent), Norway (17.4 per cent) and Germany (16.4 per cent).
Traffic to and from the BRIC economies was up 8.7 per cent, with notable growth for China (22.2 per cent) and India (10.8 per cent).
Cargo volumes continued to fall, with a drop of six per cent.
Chief Executive for Heathrow, Colin Matthews, said: “Our passenger figures underline the UK’s urgent need for a single hub airport with the capacity to meet the demand for links to emerging economies.
“The best solution for taxpayers, passengers and business is to build on the strength we already have at Heathrow.”