The study presents a developed prediction model for estimating friction losses in drip irrigation laterals based on dimensional analysis. Drip irrigation laterals with on-line barb emitters placed at different spacing. The parameters affecting the variation in friction losses in laterals were defined as dimensionless terms. The experimental work conducted at Irrigation Testing National Laboratory. AEnFll, Egypt. The Egyptian standard methods of emitters testing were used; five locally manufactured types of emitters were subjected to tests. The developed mathematical model was: Hf = 0.1467 QIUIBLZ'IJd-fiD-d.415dL—27.206d0.03 Where H, is the friction loss in a unit length of lateral (m), 0 is the lateral flow rate in L.h".. D is the lateral interior diameter (m), dis the emitter diameter (m). all. is the emitter spacing (m). and L is the lateral length (m). The developed model is valid for barb emitter type; up to 250 m of lateral length; (13:20 mm) lateral interior diameter; (0.75:1 rn) emitter spacing; (2.5:4.5 mm) emitter diameter; and emitter' average flow rate of (2:8 L.h' ). Fiesults of the developed model had a correlation factor of about 0.965 with measured data. Thus, the developed model may be effectively used to determine friction losses in drip irrigation laterals. Statistically significant differences were observed. The study showed that there are needs of more studies based on techniques considering other parameters such as water temperature.