  The decays of $\Upsilon(1s)\to\gamma(\eta',\eta)$ are studied by an approach
which has successfully predicted the ratio
$\frac{\Gamma(J/\psi\to\gamma\eta')}{\Gamma(J/\psi\to\gamma\eta)}$. Strong
dependence on quark mass has been found in the decays $(J/\psi,
\Upsilon(1s))\to\gamma(\eta',\eta)$. Very small decay rates of
$\Upsilon(1s)\to\gamma(\eta',\eta)$ are predicted.
