They use mdf for kitchen and bathroom cabinets. Since you'll have a
frame, the mdf should be fine.

Andy Jeffries wrote:

For the cabinets I was going to be using 18mm plywood (think Norm's Garage
Workshop, Mitre bench and Storage or Workshop Hutch projects).

However, I'm on a tight budget for the work and am wondering whether 18mm
MDF would hold up as well. The cabinets will be built and screwed to the
wall at the back and left so racking won't be an issue.