Yet what years are actually available? First of all civil birth registrations in Ontario didn't start until July 1, 1869 [see Statutes of the Province of Ontario 1868-1869 (1869), CAP. 30, p. 133]. Even then it took years and even decades before all areas of the province were in compliance with the law. If you are looking for birth registrations before that date then you may want to look at the church records for baptisms. Sometimes, although not all the time, the birth date is recorded as part of the baptism.
The Archives of Ontario "Tracing Your Family History: The Records" page provides the details of what birth, marriage, and death civil registrations are available. They have also made available a pathfinder called "Archives of Ontario Pathfinder to Birth Registrations" that can point you in the right direction to find the birth registration records.
As of today (January 16, 2015) the birth registrations from between July 1869 and December 1916 are available for public consultation. The 1917 indexes and registration are currently not available as they are undergoing digitization. According to the Archives of Ontario web site those microfilms should be available some time around February 20, 2015. For the birth registrations from 1918 to the present you need to contact the Office of the Registrar General of Ontario or submit a request via ServiceOntario. There are restrictions as to who can access those registrations still held by the Office of the Registrar General of Ontario.
There are also a number of other sources for helping you find the civil birth registrations in Ontario:
- Ancestry ($) presently has indexes and images of registrations in their "Ontario, Canada Births, 1869-1913" collection.
- The Ontario Vital Statistics Project (free) has abstracts of the birth registrations between 1869 and 1911 at http://freepages.genealogy.rootsweb.ancestry.com/~births/index.htm
- FamilySearch.org (free) has indexes in their "Ontario Births, 1869-1912" collection at https://familysearch.org/search/collection/1784212
If you live in Ontario often your local Latter Day Saints Family History Centre, genealogical society, public library, or archive will have the microfilms of the indexes and registrations for that area already on hand.
Finally, although they are not civil registrations don't forget about checking parish records and newspapers in the areas where your ancestors lived. For those born into the Roman Catholic faith the "Ontario, Canada, Catholic Church Records (Drouin Collection), 1747-1967" collection on Ancestry may be of some help. Just note that not all of the parishes or time periods have been included in that collection. Same goes for the "Ontario, Births and Baptisms, 1779-1899" collection on FamilySearch.