Aim: Pollen ratios are widely used to gain palaeovegetation and palaeoclimatic information from fossil pollen spectra, although their applicability has seldom been tested with modern pollen data. I used a data set of 113 lake-surface sediments from the eastern Tibetan Plateau to test the reliability of several pollen ratios. Location: The lake-surface pollen spectra cover a wide range of vegetation types (temperate desert, temperate steppe, alpine desert, alpine steppe, high-alpine meadow, sub-alpine shrub, coniferous and mixed forest) and climatic conditions (mean July temperature, T July: 4.0-17.4°C; mean annual precipitation, Pann: 104-670 mm). Methods: Lake-surface sediments were analysed palynologically, and several pollen ratios were calculated. These ratios were interpreted with respect to vegetation and climatic conditions. Results: The arboreal pollen sum (AP) was highest in samples from forested areas and was significantly correlated with Pann (r2 = 0.44). In non-forested areas, samples from large lakes and from lakes surrounded by sparse vegetation had increased AP values, suggesting that AP is a useful vegetation density indicator. Artemisia/Chenopodiaceae (A/C) ratios were lowest in desert areas and were positively correlated with Pann (r2 = 0.25). The aridity pollen index was inappropriate for inferring (palaeo-)climatic information from samples on the eastern Tibetan Plateau as it had no significant correlation with the environmental factors. Artemisia/Cyperaceae (A/Cy) ratios had a significant correlation with TJuly (r2 = 0.23), but only a weak correlation with Pann, which indicates that the A/Cy ratio is applicable as a temperature indicator. Furthermore, it is a valuable tool for the differentiation of high-alpine meadow from steppe vegetation. Main conclusions: AP sum, A/C ratio and A/Cy ratio are useful tools for qualitative and semi-quantitative palaeoenvironmental reconstruction on the Tibetan Plateau; however, the results obtained should not be interpreted quantitatively. © 2007 The Authors.