Oligo d(T)25 is covalently coupled to 1 μm superparamagnetic particle through a linkage that is stable and leak resistant over a wide pH range, thereby permitting the small-scale isolation of mRNA from crude cell lysates and tissue. The isolation occurs through the hybridization of covalently coupled oligo d(T)25 to the poly(A) region present in most eukaryotic mRNAs.