An electrophoretic survey of soluble acid phosphatases present in roots of individual plants of Anthoxanthum odoratum from a zinc-tolerant and a non-tolerant population showed that eight acid phosphatases differed in their frequency of occurrence between the two populations. No correlation was detected between the presence of any one set of soluble acid phosphatases and the index of zinc tolerance which suggests that there is no one zinc-tolerant genotype. Mine plants possessed higher soluble acid phosphatase activities than pasture plants; this could account for the higher Km values detected in mine individuals. The sensitivity of soluble acid phosphatase activity to inhibition by zinc was the same both for the four tolerant and nontolerant individuals examined though small intrapopulation differences in the degree of inhibition/ stimulation were observed. It was concluded that soluble acid phosphatases of these roots do not show adaptations to zinc, or, if they do, they are not revealed by the types of measurement made here.