• Pythium C.G.D. Nees in Carus, 1823 (unaccepted) [Family: Saprolegniales incertae sedis]
• Pythium N. Pringsheim, 1858 [Family: Pythiaceae]
• Pythium acanthicum Drechsler, 1930
• Pythium acanthophoron Sideris, 1932
• Pythium acrogynum Y.N. Yu, 1973
• Pythium adhaerens Sparrow, 1931
• Pythium allantocladon Sideris, 1932 accepted as Pythium vexans de Bary, 1876
• Pythium amasculinum Y.N. Yu, 1973
• Pythium anandrum Drechsler, 1930
• Pythium angustatum Sparrow, 1931
• Pythium aphanidermatum (Edson) Fitzp., 1923
• Pythium apleroticum Tokun., 1935
• Pythium aquatile Höhnk, 1953
• Pythium aristosporum Vanterp., 1938
• Pythium arrhenomanes Drechsler, 1928
• Pythium artotrogus de Bary, 1881 accepted as Pythium hydnosporum (Mont.) J. Schröt., 1879
• Pythium ascophallon Sideris, 1932
• Pythium boreale R.L. Duan, 1985
• Pythium buismaniae Plaäts-Nit., 1981
• Pythium butleri Subraman., 1919
• Pythium capillosum B. Paul, 1987
• Pythium carolinianum V.D. Matthews, 1931
• Pythium catenulatum V.D. Matthews, 1931
• Pythium caudatum (G.L. Barron) M.W. Dick, 2001 accepted as Lagenidium caudatum G.L. Barron, 1976
• Pythium chondricola De Cock, 1986
• Pythium coloratum Vaartaja, 1965
• Pythium complectens Hans Braun, 1924 accepted as Pythium vexans de Bary, 1876
• Pythium conidiophorum Jokl
• Pythium cucurbitacearum S. Takim., 1941
• Pythium cylindrosporum B. Paul, 1992
• Pythium debaryanum R. Hesse, 1874
• Pythium deliense Meurs, 1934
• Pythium destruens Shipton, 1987
• Pythium diacarpum E.J. Butler, 1907
• Pythium diclinum Tokun., 1935
• Pythium dictyosporum Racib., 1893 accepted as Cystosiphon dictyosporus (Racib.) M.W. Dick, 2001
• Pythium dimorphum F.F. Hendrix & W.A. Campb., 1971
• Pythium dissimile Vaartaja, 1965
• Pythium dissotocum Drechsler, 1930
• Pythium echinulatum V.D. Matthews, 1931
• Pythium entophytum Pringsh., 1858 accepted as Aphanomycopsis entophyta (Pringsh.) M.W. Dick, 2001
• Pythium erinaceum J.A. Robertson, 1977
• Pythium flevoense Plaäts-Nit., 1972
• Pythium fluminum D. Park, 1977
• Pythium folliculosum B. Paul, 1991
• Pythium gracile Schenk, 1859 accepted as Pythium diclinum Tokun., 1935
• Pythium graminicola Subraman., 1928
• Pythium grandilobatum Ali-Shtayeh & Denman ined.
• Pythium grandisporangium Fell & Master, 1975
• Pythium helicandrum Drechsler, 1950
• Pythium helicoides Drechsler, 1931
• Pythium heterothallicum W.A. Campb. & F.F. Hendrix, 1968
• Pythium hydnosporum (Mont.) J. Schröt., 1879
• Pythium hypogynum Middleton, 1941
• Pythium imperfectum Höhnk, 1953
• Pythium indicum M.S. Balakr., 1948 accepted as Pythium deliense Meurs, 1934
• Pythium indigoferae E.J. Butler, 1907
• Pythium inflatum V.D. Matthews, 1931
• Pythium insidiosum De Cock, L. Mend., A.A. Padhye, Ajello & Kaufman, 1987
• Pythium intermedium de Bary, 1881
• Pythium irregulare Buisman, 1927
• Pythium iwayamae S. Ito, 1935
• Pythium kunmingense Y.N. Yu, 1973
• Pythium lucens Ali-Shtayeh, 1985
• Pythium lutarium Ali-Shtayeh, 1985
• Pythium macrosporum Vaartaja & Plaäts-Nit., 1981
• Pythium mamillatum Meurs, 1928
• Pythium marinum Sparrow, 1934
• Pythium maritimum Höhnk, 1939
• Pythium marsipium Drechsler, 1941
• Pythium mastophorum Drechsler, 1930
• Pythium mastosporum Vaartaja & Plaäts-Nit.
• Pythium megalacanthum de Bary, 1881 accepted as Pythium buismaniae Plaäts-Nit., 1981
• Pythium middletonii Sparrow, 1960
• Pythium minor Ali-Shtayeh, 1985
• Pythium monospermum Pringsh., 1858
• Pythium multisporum Poitras, 1949
• Pythium mycoparasiticum Deacon, S.A.K. Laing & L.A. Berry, 1991
• Pythium myriotylum Drechsler, 1930
• Pythium nagaii S. Ito & Tokun., 1933
• Pythium nodosum B. Paul, D. Galland, T. Bhatn. & Dulieu, 1998
• Pythium nunn Lifsh., Stangh. & R.E.D. Baker, 1984
• Pythium oedichilum Drechsler, 1931
• Pythium okanoganense P.E. Lipps, 1981
• Pythium oligandrum Drechsler, 1930
• Pythium orthogonon Ahrens, 1971
• Pythium ostracodes Drechsler, 1943
• Pythium pachycaule Ali-Shtayeh, 1985
• Pythium paddicum Hirane, 1960
• Pythium palmivorum E.J. Butler, 1907 accepted as Phytophthora palmivora (E.J. Butler) E.J. Butler, 1919
• Pythium papillatum V.D. Matthews, 1928
• Pythium paroecandrum Drechsler, 1930
• Pythium parvum Ali-Shtayeh, 1985
• Pythium periilum Drechsler, 1931
• Pythium periplocum Drechsler, 1930
• Pythium piperinum Dastur, 1935 accepted as Pythium vexans de Bary, 1876
• Pythium pleroticum T. Itô, 1944
• Pythium plurisporium Abad, Shew, Grand & L.T. Lucas, 1996
• Pythium polymastum Drechsler, 1930
• Pythium polymorphon Sideris, 1932