The laws x m = xm(T = 0)(1 -l-fiT w2) and x m = Xm(B = 0)(1 +/3~B2), giving the effects of temperature and magnetization on the maximum solubility of 3He in 4He, are derived using the theory of normal Ferm i systems. The parameters fix and ~M are expressed in terms of measurable quantities, such as the specific heat and the magnetic susceptibility of the pure and dilute phases. Our relations are consistent with the experimental measurements of fit at SVP and predict a significant dependence of fix on pressure. Estimates of the parameter ~M are given. The effects of temperature and magnetization on the osmotic pressure are also discussed.A peculiar property of helium systems is the finite solubility of 3He in 4He down to zero temperature. 1 The experimental discovery of such an effect has stimulated many experimental and theoretical investigations of thermodynamic properties (specific heat, magnetic susceptibility, transport coefficient, osmotic pressure, maximum solubility, etc.) of 3He-nile mixtures at low temperatures (see refs. 2-7 and references therein).The aim of this paper is to investigate the effects of temperature and magnetization on the maximum solubility of 3He in 4He. The effect of temperature is well established experimentally 2 at SVP and in the low-T limit (T< 150 mK) is governed by the lawwhere xo = xm( T = 0) is the maximum solubility at T = 0 and fit = 9-11 K -2. The effect of magnetization is expected to follow a similar law:x m = x0(1 + flMB 2)(2)In the following we derive thermodynamic relations where the coefficients fit and/3M are expressed in terms of other measurable quantities, such as the specific heat and the magnetic susceptibility of the dilute and pure phases. Thermodynamic equations involving the dependence of the *INFN sezione di Padova, gruppo collegato di Trento. 311