For the year April 1993 to March 1994, serious assaults fell by 16 per cent from 143 to 120, according to a report by Income Data Services (IDS).
London Underground said the trend was due to better training and selection procedures which reduce staff's aggressive behaviour.
All front-line staff are trained in defusing aggression and courses on handling violence are available for specific jobs. Revenue control inspectors, most at risk because they have to collect pounds 10 penalty fares introduced in April, go on a two-day conflict management course to learn body language and non-verbal communication skills.
'We teach people how to diffuse an aggressive situation without becoming aggressive yourself,' said Paul Kirwin, who organises the courses.
'We teach them to talk in a calm manner, to listen to what is being said. That tends to diffuse an explosive situation. You need to be aware all the time. You can tell by a person's body movements what is going to happen next.'
According to the IDS report, a quarter of the revenue control inspectors were attacked in 1993. Others most at risk were station supervisors, 8.8 per cent of whom were attacked, and station assistants - 7.5 per cent attacked.
Over the same period, violent assaults on passengers fell from 1,115 in 1992 to 1,007 in 1993-94. Indecent assaults dropped from 262 incidents in 1992 to 253 in 1993-94. (An accounting period change makes a direct comparison difficult.)
Staff on the District and Central lines suffered more attacks.
The report praises London Underground's recruitment and training methods to weed out applicants with aggressive attitudes. Staff are also warned against being heroes and advised to back away if there is any risk of violence.
There are plans to train staff in 'tea and sympathy skills to deal with assaulted passengers before police arrive.
Despite fears that penalty fares would lead to more attacks, there has only been one reported assault.