Results from inoculation experiments have shown that the needle rust of hemlock (Tsugaspp.),Caeoma dubiumC. A. Ludwig, represents the aecial state of a new race ofMelampsora epiteaThuem. for which the nameM. epiteaf. sp.tsugaef. sp. nov. is proposed. This race differs morphologically from most species ofMelampsoraand from some races ofM. epitea. It is indistinguishable, however, from the fir rustM. abieti-capraearumTub. (another race ofM. epitea), from which it differs in its aecial hosts only. An account of the taxonomy, morphology, and life history ofM. epiteaf. sp.tsugaeis presented for the first time.