We analyse new spectra of the multiple system SZ Cam because previous studies found different values of the primary radial velocity amplitude .
The older solutions of light curves also have different ratios of secondary to primary luminosity as inferred from the observed equivalent widths of spectral lines .
We therefore reanalyse the light curves of the eclipsing pair .
Only the light curve derived by Wesselink has a solution that agrees with the observed equivalent width ratio .
The resulting parameters of the binary are discussed .
Masses of M _ { 1 } = 16.6 and M _ { 2 } = 11.9 M _ { \odot } , and radii R _ { 1 } = 9.4 and R _ { 2 } = 5.4 R _ { \odot } are derived .
We point out that radial velocities measured with the CCF method can be misleading when the method is applied to multiple systems with complex line blends .
New radial velocities are also obtained for the visual component ADS 2984 A ( HD 25639 ) .