The rate of hospital-acquired infection in Northern Ireland has dropped by a fifth to less than one in 20 patients.
The most common illness was pneumonia and those in adult intensive care were more likely to be affected, a report for the Public Health Agency added.
The prevalence of superbug MRSA and clostridium difficile (C. diff) had reduced.
Health chiefs have campaigned to encourage hand washing in hospitals as well as other hygiene measures.
Deputy chief medical officer Dr Elizabeth Mitchell said: "The report shows that Northern Ireland compares well with other parts of the UK and that we have made good progress since 2006 in the prevalence of hospital-acquired infections. However, we must not be complacent, we need to keep on improving."
According to the PHA's 2012 Point Prevalence Survey of hospital-acquired infections and use of antibiotics, 4.2% (166) of patients surveyed had an infection. The prevalence rate was around a fifth lower than that reported in the previous survey completed in 2006.
Since then there have been serious outbreaks of C. diff in Northern Ireland hospitals which prompted the holding of a public inquiry into cases in the Northern Health Trust.
The £2 million inquiry into the outbreak concluded it was linked to 31 deaths.
The most common types of hospital infections recorded in the PHA report were respiratory, like pneumonia, or stemmed from surgical sites or the urinary tract.
The number of C. diff infections was found to be much lower than six years ago. There has also been a reduction in MRSA infections from 0.9% to less than 0.1% of patients surveyed.