Isothermal remanent magnetization decay,M r(t), and ‘in-field’ growth of zero-field-cooled magnetization,M ZFC(t), with time have been measured over four decades in time at temperatures ranging from 0.25T c to 1.25T c (whereT c is the Curie temperature, determined previously for the same sample from static critical phenomena measurements) for a nearly ordered intermetallic compound Ni3Al, which is an experimental realization of a three-dimensional (d = 3) ferromagnet with weak quenched random-exchange disorder. None of the functional forms ofM r(t) predicted by the existing phenomenological models of relaxation dynamics in spin systems with quenched randomness, but only the expressions $$M_r (t) = M_0 [M_1 \exp ( - t/\tau _1 ) + (t/\tau _2 )^{ - \alpha } ]$$ and $$M_{ZFC} (t) = M'_0 [1 - \{ M'_1 \exp ( - t/\tau '_1 ) + (t/\tau '_2 )^{ - \alpha '} \} ]$$ closely reproduce such data in the present case. The most striking features of magnetic relaxation in the system in question are as follows: Aging effects are absent in bothM r t andM ZFC(t) at all temperatures in the temperature range covered in the present experiments. A cross-over in equilibrium dynamics from the one, characteristic of a pured = 3 ferromagnet with complete atomic ordering and prevalent at temperatures away from Tc, to that, typical of ad = 3 random-exchange ferromagnet, occurs asT → Tc. The relaxation times τ1(T)(τ1 ′(T)) and τ2(T)(τ2 ′(T)) exhibit logarithmic divergence at critical temperatures $$T_C^{\tau _1 } (T_C^{\tau '_1 } (H))$$ and $$T_C^{\tau _2 } (T_C^{\tau '_2 } (H))$$ ; $$T_C^{\tau '_1 } $$ and $$T_C^{\tau '_2 } $$ both increase with the external magnetic field strength,H, such that at any given field value, $$T_C^{\tau '_1 } = T_C^{\tau '_2 } $$ . The exponent characterizing the logarithmic divergence in τ 1 ′ (T) and τ 2 ′ T possesses a field-independent value of ≃16 for both relaxation times. Of all the available theoretical models, the droplet fluctuation model alone provides a qualitative explanation for some aspects of the present magnetic relaxation data