UNiAl is an itinerant antiferromagnet with a transition temperature of 18 K and a huge low-temperature Sommerfeld coefficient of 167 mJ/K2 mole U atoms. A systematic study of the pseudoternary series UNiAl1-xGa x by means of magnetic and specific-heat measurements is presented. The data are interpreted as evidence for a transition from antiferromagnetism to ferromagnetism for x>0.4 with more localized features in the Ga-rich compounds. For x=0.4 competition of ferromagnetic and antiferromagnetic interactions causes a complicated behaviour characterized by two types of magnetic transitions. Huge magnetocrystalline anisotropy is responsible for the rather anomalous behaviour of the ferromagnetic compositions.