Abstract The uv irradiation of phenanthrene 9, 10-imine has been shown to give 9H- tetrabenzo [a, c, g, i] carbazole as the major photo-product both in argon purged acetone and in dichloromethane. Phenanthrazine, N-9-phenanthrenyl-9-phenanthrenamine and phenanthrene were formed in smaller quantities. 9-Phenanthrenamine was found to be a minor by-product. N-Butylphenanthrene 9, 10-imine yielded under similar conditions ...