A photophysical analysis of 10(-4) M solutions of 7-azaindole in hydrocarbon solvents including 2-methylbutane, 3-methylpentane, ethylcyclohexane, decalin, and squalane revealed that the viability of the two-proton phototautomerism in its dimer is clearly medium-dependent. However, in all media studied, a small tunneling contribution in the photoinduced double proton transfer continues to exist at low temperatures.