The data shows that 311 people reported cocaine as their main drug of abuse in 2003, compared to 155 in 2002.
A further 2,244 people said cocaine was a secondary problem drug in addition to their main drug of abuse, such as heroin. This compares to 1,716 in 2002 an increase of 30%. The two figures combined show that 2,555 people reported cocaine as one of their problem drugs in 2003, compared to 1,871 in 2002.
Of the 2,555, some 1,929 lived in the eastern region (Dublin, Kildare and Wicklow), while 613 lived elsewhere in Ireland.
The figures taken from the National Drug Treatment Reporting System (NDTRS) were published by the Health Research Board (HRB).
In a report, Dr Jean Long of the HRB said: "Analysis from the NDTRS indicates a sustained increase between 1998 and 2003 in the number of treated cases reporting cocaine as a problem drug, particularly as an additional problem drug among opiate users."
Heroin accounts for the vast majority of abused opiates.
Dr Long said the number of cases where cocaine was the primary problem drug jumped by 262%, from 86 in 1998 to 311 in 2003.
This included 157 new cases in 2003, compared to 65 in 2002 a rise of 140%. The remainder of the case load is made up of previously treated cases.
The number of cases where cocaine was an additional problem drug rose by almost 400%, from 454 in 1998 to 2,244 in 2003.
"When cocaine was reported as the main problem drug, cannabis, alcohol and ecstasy were the most common additional problem drugs," said Dr Long.
But where cocaine was an additional problem drug, the main drug was heroin, followed by cannabis and ecstasy, she said.
Tony Geoghegan of Merchants Quay Ireland, the largest voluntary treatment centre, said: "It's probably an underestimation. It's only showing people presenting for treatment and, of course, there's an awful lot more people using cocaine and not presenting for treatment."
Mr Geoghegan said there were factors why cocaine users might not be showing up for treatment. He said they generally didn't get into difficulty as quickly as, for example, heroin users.
He said there was also a general perception that there was no treatment for cocaine.
"This isn't the case, it's just that there isn't a medical substitution treatment available, as with heroin."
He said there were counselling-based techniques, which could be used along with holistic therapies, relaxation techniques and, in severe cases, anti-depressants to treat cocaine.