Following is the ranking of world's truck manufacturers, based on production volume for calendar year 2003 as compiled by Isuzu Motors Ltd., using data by manufacturer and by country (production volume compared on single-country basis). This ranking is based on statistics compiled by Isuzu based on data available from Automobile Manufacturers' Associations of different countries on production volume of medium-duty and larger trucks, namely trucks with Gross Vehicle Weight (GVW) of 6.1 tons or higher.

One notable feature of 2003 results is that Japanese manufacturers have made quite some headway due to increased demand for trucks meeting the more stringent exhaust emission regulations.
Riding on this demand in Japan, and also due to expanded export of heavy-duty trucks to China, Isuzu Motors itself has increased its production by 19,486 units (+29%) over the previous year, reinstating itself at the top position after six years since 1997. In medium-sized truck production, Isuzu Motors has been maintaining its top position for the third consecutive year.