  We present a search for flavor changing neutral currents (FCNC) in decays of
top quarks. The analysis is based on a search for
$t\bar{t}\rightarrow\ell'\nu\ell\bar{\ell}$+jets ($\ell, \ell' = e,\mu$) final
states using 4.1 {\rm fb}$^{-1}$ of integrated luminosity of $p\bar{p}$
collisions at $\sqrt{s} = 1.96$ {\rm TeV}. We extract limits on the branching
ratio $B(t\rightarrow Zq)$ ($q = u, c$ quarks), assuming anomalous $tuZ$ or
$tcZ$ couplings. We do not observe any sign of such anomalous coupling and set
a limit of $B < 3.2%$ at 95% C.L.
