PDE7A1 is a cAMP-hydrolyzing phosphodiesterase expressed in lymphoid tissue, where its possible role during T cell activation remains unclear. We have characterized the functional relevance of PDE7A1 in the naïve (CD4+CD45RA+) and memory (CD4+CD45RO+) subsets of human peripheral CD4+ T cells during CD3/CD28-dependent stimulation. Our results indicate that PDE7A1 is expressed in resting naïve CD4+ T cells at higher levels than in the corresponding memory cells and that levels of PDE7A1 mRNA are not upregulated upon CD3/CD28 mediated stimulation of these T cell subsets. Treatment with a selective inhibitor of PDE7A1 does not impair CD3/CD28 induced activation of naïve or memory CD4+ T cells, nor does it increase intracellular cAMP in CD4+ T cells. We conclude that PDE7A1 is not required during CD3/CD28-dependent activation of naïve and memory CD4+ T cells, but cannot rule out other regulatory roles of PDE7A1 during maturation of CD4+ T cells.