The paper deals with the problem of extending the recent work of M.S.B
aouendi and L.P.Rothschild concerning harmonic functions vanishing to
infinite order in the normal direction in balls and half-spaces. Contr
ary to what one expects, we show that the B.-R. result extends neither
to arbitrary domains nor to cases when the normal is replaced by a cu
rve transversal to the boundary. The exact criterion when the result h
olds in R(2) is given.