Human protein kinase CK2 is an ubiquitous serine/threonine kinase that is typically found in tetrameric complexes consisting of two catalytic (alpha and/or alpha') and two regulatory beta subunits. Although there is growing evidence that besides the participation of CK2 in a complex series of cellular functions, this protein kinase is involved in cell viability, cell proliferation, and neoplastic transformation. In the present study, a series of 3-(substituted-benzylidene)-1,3-dihydro-indolin-2-thione derivatives and the corresponding indolin-2-one congeners were tested for their inhibition of human recombinant protein kinase CK2 in vitro. The efficacy of these compounds was compared with their inhibitory results of p60(c-Src) tyrosine kinase. It was found that 3-(substituted-benzylidene)-1,3-dihydro-indolin-2-thione derivatives are more effective than indolin-2-one congeners for the inhibition of CK2 and p60(c-Src) tyrosine kinase.