This study determined the effect of Cuisenaire Rods' approach on some Nigeria primary pupils' achievement in decimal fractions. Three hypotheses guided the study. A total of 200 Primary six pupils (that is, 6th grade) from randomly selected schools in Makurdi metropolis of Benue State of Nigeria served as the sample for the study. A Mathematics Achievement Test on Decimal Fractions (MATDF) developed by the researchers and validated by three experts with a reliability coefficient of 0.89 using K-R [subscript 21], was used for data collection. Two way Analysis of Covariance was used for analyzing the data. The results revealed that there was a significant difference between pupils taught fractions using Cuisenaire Rods' approach and those taught fractions using conventional approach with Cuisenaire rod approach being more facilitative (F[subscript 1, 199] = 12.231; p less than 0.05). Secondly, there was no significant difference between male and female pupils taught using Cuisenaire Rods approach (F[subscript 1, 199] = 3.453; p greater than 0.05). However, there was no significant interaction effect of method and gender on achievement (F[subscript 1, 199] = 1.424; p greater than 0.05). It was therefore recommended among others that teachers of mathematics should adopt Cuisenaire Rods approach in teaching mathematics in primary schools in the study area to ensure hands-on-activities and thereby contributing to enhanced understanding. (Contains 2 tables.)