3 January 1892
J.R.R. Tolkien was born in Bloemfontein, Orange Free State. His parents, Mabel and Arthur Tolkien, were British but worked in a bank in South Africa. He was a sickly child, so he and his mother and brother (Hilary, born 1894) went back to England for a change of climate in 1895. His father stayed behind, but died suddenly in February 1896.
References

J.R.R. Tolkien, [online], Available at: tolkientrail.com [Accessed: 02 January 2010]