A new 2D NMR pulse sequence for E.COSY-type measurement of J_HH coupling constants is introduced. It exploits a heteronuclear spin, e.g., ¹³C, for displacement in the ₁ frequency dimension via a large heteronuclear J coupling. The experiment is demonstrated by application to a heptapeptide at the natural abundance ¹³C level. It is suitable, for example, for measurement of ³J_HH and ⁴J_HH coupling constants in peptides and proteins.