Horizontal wells are generally perforated along a well profile of interest in order to establish flow across the casing for entry of formation fluids into the wellbore, while limiting sand production from unconsolidated reservoirs, wellbore collapse and early water or gas production. In open hole horizontal wells, the formation produces uniformly with no flow convergence towards the wellbore, and productivity index is constant along the horizontal section of the well. However, selective perforations result in multiple flow convergence regions along the wellbore, resulting in a pseudoskin effect which reduces well productivity. Hence, there is the need for optimization of a horizontal well productivity by designing the appropriate number and length of perforation intervals with minimal pseudoskin. This paper analyses the effect of selective completion on the inflow performance of a horizontal well with the aid of a reservoir simulation model (developed using EclipseTM black oil simulator) and the simple approximation method developed by Guerra and Yildiz which initially modelled selectively perforated vertical wells. Guerra and Yildiz's procedures were modified for a horizontal well under the assumption that the horizontal well is producing from a thin oil rim, allowing for a dominant radial flow. Four (4) case scenarios were used for sensitivity analysis and it was observed that both the numerical and approximation models show similar trends in performance indices. The results obtained also indicate that for the same percentage length open to flow, the higher the number open intervals, the larger the productivity index until the increment becomes insignificant, therefore subject to optimization.