The forests of the Tolfa-Ceriti mountains (Latium, central Italy) were investigated through a phytosociological approach. 249 relevés were performed and treated with multivariate analysis. 13 woodland communities were identified, of which 7 belong to Quercetalia pubescenti-petraeae, 1 to Fagetalia sylvaticae, 1 to Populetalia and 4 to Quercetalia ilicis. The thermophilous Turkey oak-forests occurring on the trachytic hills of the Ceriti Mountains and on the flysch substrates of the Tolfa Mountains were included in Rubio peregrinae-Quercetum cerridis ass. nova. Quercus cerris and Fraxinus angustifolia subsp. oxycarpa woodland communities of the footslopes have been ascribed to Fraxino oxycarpae-Quercetum cerridis, while the widespread mesophilus Turkey oak forests have been ascribed to Melico-Quercetum cerridis. Cephalantero longifoliae-Quercetum cerridis has been restricted to acid and oligotrophic soils. Quercus petraea woodlands, occurring on trachytic substrates have been described as a new association named Carici olbiensis-Quercetum petraeae ass. nova. All these mixed oak woods have been included in the alliance Crataego laevigatae-Quercion cerridis Arrigoni 1997. The nomenclatural problems concerning the prior name Teucrio siculi-Quercion cerridis Ubaldi 1988 are also discussed. The beech forests of the higher altitudes have been included in Fraxino orni-Fagetum sylvaticae, while the Alnus glutinosa ravine woodlands have been described as belonging to the new association Polysticho setiferi-Alnetum glutinosae. Secondary communities of Acer monspessulanum and Acer campestre developed on flysch substrates, and of Erica arborea and Arbutus unedo (Erico-Arbutetum unedonis) developed on trachytic substrates, have also been identified. Finally two types of Quercus ilex wood have been identified: Cyclamino repandi-Quercetum ilicis, on sandstones, and the new association Arbuto unedonis-Quercetum ilicis ass. nova on volcanic soils. This latter community can be considered as a coenological and geographical vicariant in central Italy of the sicilian Erico-Quercetum ilicis. Fitocenološko so bili raziskani gozdovih na pogorju Tolfa-Ceriti (Lacij, osrednja Italija). Izdelano je bilo 249 fitocenoloških popisov, ki so bili obdelani z multivariantimi metodami. Ugotovljenih je bilo 13 gozdnih združb, od katerih jih 7 uvrščamo v red Quercetalia pubescenti-petraeae, 1 v red Fagetalia sylvaticae, 1 v red Populetalia in 4 v red Quercetalia ilicis. Termofilni cerovi gozdovi, ki jih najdemo v gričevnatem svetu pogorja Ceriti in se razvijejo na flišu v pogorju Tolfa, so vključeni v asociacijo Rubio pereginae-Quercetum cerridis ass. nova. Gozdovi cera (Quercus cerris) in ozkolistnega jesena (Fraxinus angustifolia subsp. oxycarpa) na vznožjih so uvrščeni v združbo Fraxino oxycarpae-Quercetum cerridis, medtem ko so široko razširjeni mezofilni cerovi gozdovi uvrščeni v združbo Melico-Quercetum cerridis. Združba Cephalanthero longifoliae-Quercetum cerridis je razširjena le na grušču na kislih in oligotrofnih tleh. Gradnovi gozdovi, ki se pojavljajo na trahičnem substratu, so uvrščeni v novo asociacijo Carici olbiensis-Quercetum petraeae. Vsi obravnavani mešani hrastovi gozdovi so vključeni v zvezo Crataego laevigatae-Quercion cerridis Arrigoni 1997; poleg tega pa obravnavamo tudi starejše ime Teucrio siculi-Quercion cerridis Ubaldi 1988. Bukove gozdove, ki se pojavljajo na večjih nadmorskih višinah, uvrščamo v združbo Fraxino orni-Fagetum sylvaticae, medtem ko jelševe gozdove, ki jih najdemo po grapah, uvrščamo v novo asociacijo Polysticho setiferi-Alnetum glutinosae. Ugotovili smo tudi sekundarni združbi, in sicer na flišu združbo trokrpega javorja (Acer monspessulanum) in maklena (Acer campestre) ter na trahičnem substratu združbo drevesaste rese (Erica arborea) in jagodičnice (Arbutus unedo) - Erico-Arbutetum unedonis. Ugotovili smo tudi dva tipa gozdov črničevja (Quercus ilex): Cyclamino repandi-Quercetum ilicis na peščenjakih in novo asociacijo Arbuto unedeonis-Quercetum ilicis ass. nova na vulkanskih tleh, ki jo lahko obravnavamo kot cenološko in geografsko vikariantno združbo združbe Erico-Quercetum ilicis, ki jo najdemo na Siciliji.