"Waiting times like these are just not acceptable," said the SNP Holyrood leader, who said the statistics were from official figures supplied to her over the Easter break.
The exchanges between Mr McConnell and Ms Sturgeon came after a Holyrood debate on drugs.
Nicola Sturgeon began by congratulating Strathclyde Police on a series of dawn raids in Glasgow earlier today and went on to seek Mr McConnell's views on addicts getting access to treatment.
Ms Sturgeon acknowledged there had been success in tackling the supply of drugs, and the attempts to improve rehabilitation and treatment. But she said that before addicts could be treated, they had to be assessed.
Ms Sturgeon told MSPs:
"Information provided to my office during the Easter break by the government statistics department shows that in the last quarter of last year, of the 7,000 new addicts referred for treatment, nearly 1,000 of them waited more than six months just to be assessed.
"Four hundred of them waited longer than a year just to be assessed for treatment.
"When we have a strategy that rightly encourages addicts to seek help and take personal responsibility for their lives, waiting times like these are just not acceptable."
In the Holyrood debate earlier, SNP MSPs argued that relaxing the rules on drug misuse would only make the drugs situation in Scotland worse.
SNP MSP Stewart Stevenson said a large study carried out in the Netherlands showed legalising cannabis did not reduce the use of harder drugs.
He said the study revealed that Amsterdam, with its relaxed approach to cannabis, had the highest use of not only that drug but also other illegal drugs.
Mr Stevenson, Banff and Buchan MSP, said: "There will be some benefit in the sort of approach they take in Amsterdam in police time, but it doesn't touch upon drugs use.
"The study that has been done in the Netherlands shows that legalising cannabis actually does not reduce hard drug use."
And he stressed the need for various treatment options to be available to help addicts.
He said: "There is no one-size-fits-all option, if only there was we would have solved it by now."
Maureen Watt, in her maiden speech following her swearing in as a North East Scotland MSP yesterday, called for more residential drugs rehabilitation places and questioned the "controlled drug abuse" of prescribing methadone.
Ms Watt said she had witnessed first-hand the "human misery" caused by drugs for the last 14 years as a prison visitor at Craiginches in Aberdeen.
And she argued that neither short jail terms nor methadone was the answer for addicts.
Ms Watt said: "The benefit to the drug user and society of becoming drug-free greatly outweighs the benefits of controlled drug abuse.
"Residential rehabilitation has been shown to be the most effective in facilitating recovery and yet is available to only a tiny proportion of addicts in Scotland.
"I agree with colleagues that it is not a case of one-size-fits-all.
"The methadone programme alone, for an estimated 20,000 addicts, is at a cost of £12 million.
"How much better if this money could be redirected to provide residential rehab services?"
Ms Watt said private provision of such programmes was "patchy and unregulated" and called for greater publicly funded residential rehabilitation places.