Magnetic measurements were performed on GdxLa1-xNi5 compounds in the temperature range 1.7-300K and fields up to 7 T. The compounds with x greater than or equal to0.2 are ferrimagnetically ordered. The nickel moment at 1.7K decreases gradually and is nil for LaNi5. LaNi5 shows a behavior typical for a nonsaturated spin fluctuation system. Electronic structure of ordered Gd3Ni15, Gd2LaNi15 and GdLa2Ni15 compounds were calculated by using the ab-initio tight-binding linear muffin-tin orbitals method in atomic sphere approximation. The determined saturation moments per formula unit agree well with those experimentally determined.