Patient safety at East Midlands Ambulance Service (EMAS) is improving, according to an independent report.
It said progress had been made on cleanliness and infection management, but there was still work to be done.
The review followed a Care Quality Commission (CQC) spot-check in August 2009 which discovered a catalogue of hygiene problems, including dirty ambulances and equipment.
EMAS has also been criticised for having England's worst response times.
The independent report, published on Tuesday, was commissioned by NHS East Midlands and NHS Derbyshire and covered patient safety, management and infection prevention and control.
The report states that: "There is demonstrable improvement in the management of infection prevention and control. The cleanliness of vehicles and storerooms were seen to be good."
EMAS medical director Dr James Gray said: "We've really come a long way now and are starting to show really high quality practice in some areas while having other areas where we still have a journey to take to really become great."
The report makes a series of recommendations on managing staff to help EMAS to continue to improve and the results of another CQC check are expected to be published early in 2011.
An improvement plan to combat slow response times is also being implemented.
East Midlands Ambulance Service covers six counties and handles more than 600,000 emergency calls a year.