The mishap occurred when the jeep and the mini-truck collided head-on near Dongla village in the district, Badnagar police station in-charge R K Jain told reporters.
The victims were passengers of the jeep, he said.
The deceased have been identified as Dashrath (45), Beeru Singh (34), Ramesh Lal (55) and Rupesh Kumar, he said.
The injured persons, including one seriously hurt, were admitted in Ujjain's district hospital for treatment.