The option to complete the census questionnaire via the Internet is one of the major changes for the 2006 Canadian Census of Population. The 2004 Census Test tested most systems and operations in preparation for the 2006 Census, including the Internet collection method. After the 2004 Census Test, analyses were carried out to measure the impact of the Internet collection method on the data as compared with the traditional paper collection method. The impact was analysed on the basis of item response rates and response content. The analysis compared the data of people who were present in both the 2001 Census and the 2004 Census Test, where the 2001 data were collected by paper and the 2004 data were collected via the Internet. These comparisons enabled us to measure the Internet mode effect on item response rates and content. This paper presents some features of the Internet questionnaire and the analysis of the 2004 Census Test data.