Government chief whip Tom Kitt urged the Irish public to play their part in contributing to the success of the census, which takes place on Sunday night.
He said this will be a particularly crucial census, taking place at a time of unprecedented demographic and social change in Ireland. It is possible that the population could be as high as 4.2 million which would be the highest since 1871, 135 years ago.
Mr Kitt said the census will also provide precise figures on the number of non-Irish nationals living and working here.
"In recent years we are all aware of a much changing Ireland - an Ireland that has seen a huge influx of non-Irish nationals which has created a new, vibrant, multicultural society.
The Minister said population statistics are essential for planning the provision of essential services such as healthcare and education and will also provide information on employment trends.
"In addition the census will inform us as to other more local needs such as retail outlets and social amenities.The results will greatly help the Government with special strategic planning."
The Minister reassured the public of the confidentiality of all information collected from individual households and businesses for the census and said this was guaranteed by law.
Preliminary results will be published in about three months.