The distribution of genetic variation at nine enzyme gene loci in the European range of silver fir is studied with the aim to characterize the genetic basis of this species' adaptive potentials. For this purpose, the basic notions of physiological and evolutionary adaptive potential are briefly discussed in connection with operating and latent genetic potentials of populations. A measure for the quantification of latent genetic potential is introduced together with a procedure that evaluates the detective power of the samples taken. The results obtained from application of this measure are in striking accordance with earlier suggestions based chiefly on ecophysiological traits, and which assume both low physiological and evolutionary adaptive potential in the central and northeastern European populations of silver fir. Moreover, careful consideration of the structural and functional characteristics of the enzymes used in the present study support the assumption that they are not selectively neutral, and in one case it can indeed be demonstrated that the two alleles at a locus are very likely to be under selection for temperature differences between central and southern European populations.