Selective PDE4 inhibition is achieved by 4-(substituted-phenyl)-2-pyrrolidinone compounds. The compounds exhibit improved PDE4 inhibition as compared to compounds like rolipram and show selectivity with regard to inhibition of other classes of PDEs. The compounds of the present invention are of formula I: ##STR00001## wherein R.sup.1, R.sup.2, and R.sup.3 are as defined herein.