AbstractThe singlet‐singlet intramolecular energy transfer between naphthalene moiety and dansy! group held apart by a rigid steroid bridge was investigated for two molecules: β‐(1‐naphthyl) acetoxy‐17α‐dansyl‐Δ5androstene (3a) and 3β‐(1‐naphthyl)acetoxy‐17 β‐dansyl‐Δ5androstene (3b). The rates of energy transfer for 3a and 3b in cyclohexane are 6.9 × 106and 1.1 × 108s−1respectively. The difference in energy transfer rate between 3a and 3b is attributed to the different donor‐acceptor separation and orientation. The ratio of the two epimers in the synthesized product mixture was obtained from th