Depending on the offence, you may be considered "rehabilitated" for the purposes of determining admissibility to Canada after 10 years have passed.
What is rehabilitation?
Rehabilitation removes the grounds of criminal inadmissibility. Rehabilitation means that you lead a stable lifestyle and that you are unlikely to be involved in any further criminal activity.
You are eligible to apply for rehabilitation if you have:
committed an act outside of Canada and five (5) years have elapsed since the act;
been convicted outside of Canada and five (5) years have passed since the end of the sentence imposed.
Eligibility for rehabilitation
This section gives a summary of the type of offences and length of rehabilitation periods.
If you were convicted of an offence outside Canada that, if committed in Canada, would be an indictable offence punishable by a maximum term of imprisonment of less than ten years:
You are deemed rehabilitated: at least ten years after completion of the sentence imposed.
You are eligible to apply for rehabilitation: five (5) years after completion of the sentence imposed.
http://www.cic.gc.ca/English/informa...s/5312ETOC.asp
DUI with no aggravating factors has a maximum sentence of 5 years in Canada. Therefore, you are deemed rehabilitated 10 years after the completion of your sentence.