An abrupt global warming event has been recorded in many parts of the world in sediments of Latest Maastrichtian age between 65.45-65.10 Ma. This warm event was documented here at a section near Ziyarat-kola in Central Alborz based on analysis of planktonic foraminifera. An unusual abundance of normally large-size species such as Globotruncana arca, Globigerinelloides subcarinatus, Pseudoguembelina hariaensis and Rugoglobigerina rugosa in small-size fraction (63-150) was recorded. A similar trend of increasing in relative abundance of some opportunist species such as Guembelitria spp. was also recorded. At the same time, Laeviheterohelix dentata a long ranging dominant species, decreases considerably reflecting a high stress environmental condition as warming. Palynological studies show an increase in fungal spore and in thermophilic species confirming the result gained from foraminiferal analysis.