The invention provides a reliable method for recovering RNA from a formalin-fixed, paraffin-embedded biological tissue sample comprising: a) deparaffinizing the sample, b) contacting said sample with a solution comprising an effective concentration of proteinase K and heating the sample in said solution to a temperature in the range of about 30 to about 60.degree. C., for a time period of about 12 to 20 hours, c) adding an effective concentration of proteinase K to the solution obtained from b) for a time period of about 5 to about 30 minutes at a temperature range of about 40 to about 75.degree. C., and d) recovering said RNA from said solution. The additional step c) of digestion improves significantly the recovery of RNA.