The lawyers have received international support for their cause
A court in Vietnam has rejected appeals by some of the country's most prominent dissidents, including human rights lawyer Le Cong Dinh.
Among the three activists who appeared before the court, only one was given a more lenient jail term. The fourth, Nguyen Tien Trung, did not appeal.
The dissidents were given lengthy sentences last January for plotting to overthrow the Vietnamese government.
Their case triggered fierce criticism from the US and the European Union.
The trial of the four democracy activists is perhaps the most prominent court case in Vietnam in recent years.
Mr Dinh, a reputable lawyer, is well known not only in Vietnam but also overseas, and there have been numerous calls from international organisations for his early release.
But the appeals court in Ho Chi Minh City decided to uphold his sentence of five years in jail, followed by three years of house arrest.
Another dissident, businessman Tran Huynh Duy Thuc, also saw his sentence of 16 years upheld.
Only Le Thang Long, the third dissident, had his jail term cut by a year and a half.
Before the hearing on Tuesday, the dissidents' families said they hoped that the court would show clemency because of the high profile of the case.
But by quashing their hopes, the Vietnamese government again confirmed that there would be no tolerance of political dissent, especially in the run-up to the Communist Party Congress in January 2011.