Abstract: Clamping unit for a molding machine, in particular for an injection-molding machine, with a machine frame, an end plate arranged on the machine frame, a platen movably mounted on the machine frame, a stationary platen arranged on the machine frame, at least two, in particular four, tie bars, via which a clamping force can be transmitted, and a mold height adjustment apparatus for adjusting the mold height for a molding tool which can be or is fitted on the platen, wherein the mold height adjustment apparatus has i. a rotatable adjustment element gripping on at least one tie bar, ii. a drive device for rotating the rotatable adjustment element and iii. a locking device for securing the rotatable adjustment element against a rotational movement relative to the at least one tie bar.