Abstract Magnetic measurements were performed on U1−xRxAl3 compounds with R = Gd and Dy in the temperature range 400–600 K and fields up to 7 T. UAl3 shows a spin fluctuation-type behaviour. The effective uranium moment, determined in the high temperature range, is 3.62 μB. When replacing U by Gd or Dy, at low temperatures the susceptibilities follow a Curie-Weiss-type behaviour. The effective uranium moments decrease when the rare earth content is increasing. This behaviour is attributed to gradual quenching of spin fluctuations.