Too many trusts are still not responding to patient safety alerts in England, campaigners say.
Alerts are issued when potentially harmful situations are identified in health settings, such as the risk of overdoses or using medical equipment.
Department of Health data showed there were over 650 cases of NHS trusts not complying with alerts within deadline.
This is a 50% fall from last year, but Action against Medical Accidents said there was no excuse for non-compliance.
The charity first highlighted the issue last year when it obtained the figures under a freedom of information request.
But now the government has started publishing the figures itself.
The latest data, from January, showed that there were 654 instances of patient safety alerts not having been complied with - half the figure from August.
In total there were 203 trusts which had failed to comply with at least one alert, while five trusts had not complied with 10 or more alerts.
Peter Walsh, chief executive of Action against Medical Accidents, said: "There can be no excuse for not implementing these alerts. Each alert not complied with means patients are being put at unnecessary risk. Lives are being lost as a result."
But he added: "We welcome the fact that as a result of the pressure we have brought to bear, there has been a significant improvement in compliance."
A Department of Health spokesman said: "Although progress has been made, much more needs to be done across the system. We expect trusts to comply with safety alerts."