This study evaluated the Basic Science textbooks used at Universal Basic Education Schools in Benue State, Nigeria using naturalistic evaluation design. The purpose of the study was to ascertain if the content coverage, learning activities, chapter summaries and study questions are consistent the prescribed core curriculum for teaching Basic Science. Four research questions guided the study. The seven approved Basic Science textbooks were use d for the study. 81 Basic Science teachers from one Local Government each representing two Education Zones in Benue State were purposively sampled for the study. The instrument used for data collection was the 8-point evaluation model, an update of Quantitative Approach to Content Evaluation of Science Textbooks (QACEST). The 8-point model was used to answer research questions. The results of the findings showed that: on topical coverage, Effective Basic Science textbook had the highest topical coverage index of 0.90 while Basic Science textbook had the lowest topical coverage index of 0.79. In terms of learning activities, Basic Science textbook had the highest learning activity index of 0.70 while Fundamentals of Basic Science had the lowest learning activity index of 0.52. On chapter summaries, Fundamentals of Basic Science had the highest chapter summary index of 0.88 while Effective Basic Science had the lowest chapter summary index of 0.60. On study questions, Classical Basic Science had the highest study question index of 0.69 while Fundamentals of Basic Science had the lowest study question index of 0.61. Based on the findings, it was recommended among others that there should be periodic evaluation Basic Science textbooks to ensure that the best textbooks are approved and used for teaching and learning of the subject considering the fact Basic Science is the foundational science subject that determines the success or failure of future scientific studies in Nigeria.