The theoretical effects of a finite slope condition band crossing on the direct exciton energy levels of wurtzite compounds is investigated. The lack of an experimental confirmation of these effects places an upper limit of about 10−10ev‐cm on the slope of the conduction band atk= 0 in CdS, and a slightly larger limit in CdSe. Theoretical estimates of these slopes are also calculated. Another possible method of observing the magnetic effects due to the nonzero wave vector of the excitons is noted. The striking increase of the exciton oscillator strength in CdSe in a magnetic field is attributed to the magnetic compression of the excitons. A brief comparison of experimental energy band parameters for CdS and CdSe is given.