Let f = ( fn , Fn ) n≥0 be a martingale on some filtered complete probability space (Ω, F , P ) with the usual conditions. We define the iterated martingale transforms I ( m )( f ) = ( In ( m ), ( Fn )) ( m ≥1) with respect to f , the discrete analogues of the iterated stochastic integrals. We obtain the Lp (1≤ p )-estimates of I ( m )( f ) || I ( m )*|| p ≤ (4 mp ) m || S m ( f )|| p
and we also characterize a continuous martingale by the limit of the iterated martingale transforms.