The Calima River Basin is part of the Chocó Biogeográfico Ecoregion in the Pacific Coast of Colombia. Here, we compile a bat species checklist recorded for the Basin and describe the bat diversity patterns found in the mid-Calima Basin (the gradient from 300 – 1,400 m a.s.l.). The checklist comprises 55 bat species for the Basin. In the mid-Calima, 31 bat species occur (permanently or seasonally). Our results show complementary diversity patterns of bat assemblages living below and above 1,000 m. We also identified an overlap zone between 800 – 1,200 m a.s.l. where at least three pairs of sister species coexists. The sampled area is located where the Chocó and the Andes biogeographical regions are connected. The Calima River Basin has high bat richness, high variation in species composition along the elevational gradient, and harbours threatened and endemic species, highlighting its importance for conservation.