An efficient method is described for the isolation of mouse hair follicle mRNAs. The RNA contains two peaks of mRNA activity, 11S and 18S. The larger-sized group of mRNAs encodes keratins of 46K, 47K, 58K, 59K, and 63K Mr. cDNAs were prepared using the follicular mRNAs as templates and cloned to produce a library. Initial screening of this library has identified five acidic and six basic mouse hair keratin clones.