The continuing quest for an organic unimolecular rectifier is reviewed. Langmuir‐Blodgett (LB) films of D‐&sgr;‐A molecules (D=one‐electron donor, &sgr;=carbamate, A=one‐electron acceptor) have been prepared, and electrical current measurements through monolayers have been measured, both by macroscopic means and by scanning tunneling microscopy. A definitive experimental proof of the 1974 Aviram‐Ratner Ansatz still eludes us.