This paper presents the results of a taphonomic study of Holocene diatoms in the Llano Grande Basin, Páramo de Frontino, which is located 3,460 m above sea level in the northwestern Andean Cordillera (6º29'N/76º6'W), Colombia.Samples measuring 1 cm 3 from 57 levels distributed over a core depth of 8.5 m (LLG3) were randomly collected from sediment representing a paleolake that developed on the Llano Grande Basin.The density of diatoms and the number of fragmented and dissolved valves were estimated from 10 μL of each sample.A high variability in the density and preservation of the diatom assemblages was verifi ed along the core, which is related to temperature variation, macroinvertebrates grazing, volcanic ash infl ux, and water-level fl uctuations over the 11.000 C 14 years BP.Fragmentation was higher than dissolution, which indicates the predominance of lotic environments and grazing.The substantial decrease in the diatoms on specifi c level is interpreted as a result of the limitation of silica, decreased water levels, intense herbivory, dry environment or dissolution.In these cases, it is impossible to recognize most of the periphytic diatoms due to the high degree of fragmentation of the frustules.The authors conclude that the high degree of variation of the taphonomic damage in the diatoms of Páramo de Frontino represents different environmental events along the Holocene.Therefore, in the early Holocene, input from ash and high temperatures favored reproduction, which resulted in the high density of diatoms.In the last 4,000 years, the water level in the lake has decreased, and probably the predation on diatoms has increased as evidenced by the increasing of fragmentation of the state 3.