Rhodium(I) complex catalysed hydroformylation of unsaturated silyl enol ethers leads to products of an intramolecular aldol addition in a one-pot procedure. Thus β,γ- or γ,δ-unsaturated silyl enol ethers undergo tandem hydroformylation/Mukaiyama aldol reaction to form cyclic O-silylated aldol adducts with high selectivity and good yields.