The irradiation of dilute solutions of 3- and 4-styrylisoquinoline and 1-(3-pyridyl)-2-(4-quinolyl)ethylene in hexane or cyclohexane with ultraviolet light gave, as major products, the expected polycyclic aza-aromatic compounds, benzo[a]phenanthridine, benzo[c]phenanthridine, and benzo[c]-2,8-phenathroline respectively. The attempted photocyclisation of 2-styrylquinoline and 1-(3-pyridyl)-2-(2-quinolyl)ethylene failed to give cyclised products.