The agency said it had arrested some of Scotland's biggest dealers
About £21m of illicit drugs have been seized in Scotland over the past year - almost three times the amount taken from the streets last year.
The annual report from the Scottish Crime and Drugs Enforcement Agency also showed an increase in the number of arrests for drug offences.
They included 49 people described as being among Scotland's most serious and dangerous criminals.
However, the drug seizures were still lower than the agency's targets.
The agency said it had recovered £15.8m of Class A substances such as heroin and cocaine, along with £5.1m of cannabis. The total amount of drugs seized in the previous year was £7.5m.
Criminal assets worth £4,659,840 were also identtified for restraint - an 8% increase on last year.
SCDEA director general Gordon Meldrum told BBC Radio's Good Morning Scotland programme that the agency had focused much of its attention on the major players at the top of Scotland's drug dealing networks.
He said: "These are people who from our intelligence, and our operations, essentially sit at the top of the criminal tree, those people who maybe orchestrate much of that criminal activity.
"Many of those people will not necessarily reside in Scotland or visit Scotland that often. A lot of those people will actually reside elsewhere in the UK, across central Europe and other in parts of the world."
Earlier this year, a study by the UK Drug Policy Commission raised serious questions about the role high profile drug seizures play in the war on drugs, and argued that their impact on the drug trade was negligible.
Justice Minister Kenny MacAskill has said the forthcoming Criminal Justice Bill will include tougher measures against those running criminal gangs, and will help police and the courts tackle the financial basis of criminal empires.
And Mr Meldrum accepted the success of the agency should not be measured purely on the amount of drugs it seized.
He added: "I would like to know to more about the entire serious and organised criminal network within Scotland and concentrate on maybe the top 10% or 20% of that network and judge impact against that as opposed to necessarily the amount of drugs we seize.
"The one thing I would say in terms of drugs raids within this country is if you live in a street or in a close where there is consistent drug dealing night after night, day after day, very often the only respite you get is when police officers come through that door and arrest that drug dealer."
Mr MacAskill said: "Drugs and the criminals who peddle them continue to bring misery to our communities. That is why the Scottish Government set up the Serious Organised Crime Taskforce, which meets again today, to work with the SCDEA, our eight forces and other law enforcement agencies to tackle this menace.
"The Scottish Crime and Drug Enforcement Agency has had an impressive track record in bringing down these organised gangs and crime networks. The SCDEA is to be congratulated on its work over the last year which has seen the removal from our streets of 170 criminals, including 49 of the most dangerous figures and an increase in the amount of Class A drugs seized."