The Tubara beds of the department of Atlantico, northern Colombia, contain a foraminiferal fauna of 83 species and varieties of which 15 are new and are described here. Two microfaunal zones are recognized: the lower, Zone I, is placed in the upper part of the middle Miocene and correlated with the Gurabo formation and its equivalents in the Dominican Republic; the upper, Zone II, is placed in the upper Miocene and provisionally related to the Bowden and Buff Bay assemblages and also to the fauna of the upper part of the Choctawhatchee formation. Evidence of connection between the Caribbean and the Pacific in lower Miocene and upper middle Miocene time is discussed.