We have investigated the effects of annealing on the uranium intermetallic compound UAu2Si2. The physical properties of both the annealed and as-cast samples were studied from 5 to 300 K. Both the resistivity varrho(T) and low-field magnetic susceptibility χ(T) of the as-cast sample show anomalies at 18 K and at 82 K; whereas the heat capacity C(T) shows only an anomaly at 20.5 K. The varrho(T) and χ(T) of the annealed sample displays a low-temperature anomaly around 20 K; and a complex magnetic phase transition between 48 K and 55 K was observed. A sharp anomaly of C(T) in the annealed UAu2Si2 can be seen at 21.5 K. The annealed sample shows Fermi-liquid behavior below 10 K with a coefficient of the quadratic term in the temperature dependence of the resistivity being 11.5 μΩ-cm K−2. The low temperature electronic specific heat coefficient γ of the annealed sample is 92 mJ mol K−2. We infer that UAu2Si2 has heavy-fermion behavior with ferromagnetic ground state, which is an uncommon behavior in the uranium intermetallic compounds.