A number of novel pyrazolomorphinans have been synthesized in excellent yields by the reaction of the enolic morphinan diketones 6 with various hydrazines. Hydrazine dihydrochloride led to the N-unsubstituted tautomeric pyrazoles 7a in equilibrium with 9a and 8a in equilibrium with 10a which could not be separated. Arylhydrazines on the other hand furnished the regioisomeric pyrazolomorphinans 7 and 9 as well as 8 and 10, which could be isolated and characterized. The structures of the new compounds were clarified by their spectra, the assignment of the regioisomeres was achieved by determination of NOE enhancements. Compounds 6a, 7c, 8b and 10c have been evaluated for their affinity at mu and kappa opioid receptors in radioligand binding assays. Their ability to inhibit [3H] DAMGO binding to mu and [3H] U 69,593 binding to kappa opioid receptors has been found to be comparable with that of codeine.