Tropical inland lakes harbour a variety of waterbirds and provide a wintering habitat for Palaearctic and other migratory birds. However, the importance of the lakes as a temporary site for migrant bird populations has not been adequately studied. The point count method was used to study waterbird species diversity and abundance in Lake Ashenge, in the semi-arid region of northern Ethiopia, with the main aim to underscore the lake's importance as a stop-over site for Palaearctic and other migratory birds. A total of 36 species belonging to 14 waterbird families were encountered. Fifteen of the species were resident birds, including the endemic Wattled Ibis (Bostrychia carunculata), and 14 of the species were Palaearctic migrants, including the globally Near-Threatened Ferruginous Duck (Ayithya nyroca) and Maccoa Duck (Oxyura maccoa). Significant temporal variation in diversity and abundance was observed during the study period; diversity was highest (Shannon-Wiener H′ = 1.98) in the dry season (December/January) and lowest (H′ = 1.11) in the rainy season (August/September), whereas mean abundance was highest (c. 4219 individuals) in the post-rainy season (October/November) and lowest (c. 2631 individuals) in the dry season. Increased abundance of Palaearctic species towards the dry season increased species diversity,but may have caused displacement of resident birds resulting in lower overall abundance in this season. This study provides a new distributional record for Maccoa Duck, highlights the significance of the lake for several waterbird species and calls for its protection.