Aim: To describe the external and internal root anatomy of maxillary first and second premolars in a Nigerian population using decalcification, clearing and staining technique. Materials and Methods: Ninety-six maxillary first premolars and one hundred and sixteen maxillary second premolars from 212 consenting adults indicated for extraction were studied. They were then decalcified, cleared and stained in vitro. The number of roots, tooth length, direction of root curvature, number of canals, canal configuration and number of apical foramina were noted. Results: The maxillary first premolars were mostly two rooted (70.8%) while maxillary second premolars predominantly had one root (82.8%) (p=0.001) and two canals. The mean tooth length for the maxillary first (21.87mm) and second (21.56mm) premolars was determined. There was no statistically significant difference between tooth length and gender in the teeth studied. The majority of single rooted teeth studied were curved distally, with more variable canal configurations than two rooted specimens. Overall, type IV configuration was the most prevalent in both maxillary first (81.2%) and second premolars (58.6%). Lateral canals were present in 29.2% of maxillary first and in 34.4% of second premolars studied. Inter- canal communications were observed in 20.8% of maxillary first premolars and 6.8% of maxillary second premolars. Root canals exited with multiple foramina in both maxillary first (83.3%) and second (62.1%) premolars. Conclusion: Maxillary first premolars were mostly two rooted while maxillary second premolars predominantly had a single root in the studied population. Also, the majority of the teeth studied had two canals and type IV canal configuration. Anatomic variations in these teeth should be borne in mind when carrying out endodontic treatment. Keywords: Maxillary premolars, root canal, morphology, Nigerian