  We present preliminary results for the mass of the 6q flavor-singlet state
($J^P=0^+$, $S=-2$) called H-dibaryon, calculated in quenched QCD on $16^3$x30
and $24^3$x30 lattices with improved gauge and fermion actions (Symanzik
improvement, Clover action). For both lattice sizes we applied the fuzzing
technique to enhance the overlap with the ground state. We observe a H-mass
above the $\Lambda\Lambda$ threshold for strong decay. The difference in mass,
$m_H - 2m_\Lambda$, increases with increasing lattice size.
