This paper presents a computer model results for investigation of the effect of pressure in the last effect (Pv3) on the performance of triple-effect evaporator (TEE). The model was designed to address steady state conditions. The study covered forward feed evaporation mode, with wide range of evaporator capacity (500-10,000 kg/h). The temperature of steam was varied between 100 and 400 kPa-g while the pressure in the third effect was varied from 10 to 130 kPa-abs. The boiling temperatures in the three effects varied logarithmically with Pv3. The overall temperature difference decreased with Pv3. While V1 and V2 decreased with Pv3, V3 increased with Pv3. The steam requirements decreased while steam economy increased with Pv3. The total heat transfer surface area requirements, number of tubes required, down comer diameter and tube sizes increased with Pv3 with different polynomial function coefficients depending on pressure of the steam. It was concluded that with exception of boiling temperatures which increased logarithmically with Pv3, other performance parameters varied with Pv3 according to fourth degree polynomial functions. The goodness of fit was assessed by using the R2 values, which ranged between 0.9990 and 1.0.