The present title “Hepaticae of Nilgiri hills, Western Ghats (India)”Vol.-I, provides the first comprehensive account of diversity in the terrestrial liverworts of Nilgiri hills. It incorporates a critical morpho-taxonomic and ecological observations of terrestrial taxa supplemented with relevant illustrations. Short descriptions of each unit of classification including order, suborder, families, subfamilies and genera of hepaticae with keys to segregate them have been provided. Each species has been dealt with as far as achievable complete morpho-taxnomic details and relevant synonyms. It also incorporates the type locality of the species, range of their distribution in India and elsewhere (in the world), characteristics of the species, reference to specimens examined and discussion showing affinity with closely related taxa. Besides combination of characters, some modern criteria have also been applied to evaluate the correct taxonomic status of each species. Some closely related species difficult to be differentiated on classical criteria were investigated for SEM details of sporoderm architecture of spores which provide added information for clear elucidation of the taxa.