Fossil terrestrial gastropods have proven to be reliable indicators of palaeoenvironments. Fossil assemblages from the Early Miocene of East Africa have similar compositions to extant snails assemblages from the same region, although there are some notable absences in the fossil record. The fossil gastropods from the Legetet Formation, near Koru, Western Kenya, comprises ca. 50000 specimens belonging to at least 48 taxa. Such a rich assemblage rivals the diversity in optimal extant snail territories, such as tropical forest. The present note describes and interprets the Early Miocene Legetet Gastropoda. They reveal that the region was covered in perennially humid forest at the time of deposition, and that it was an upland more than 1200 metres above sea-level. Snails were evidently breeding at the site, as shown by the abundance and variety of snail eggs found in the deposits.