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Bromine hyperfine and quadrupole fine struture has been observed in the 3 cm microwave-optical double resonance (MODR) spectrum of the photoexcited $\mathrm{<mrow\; data-mjx-texclass="ORD">3</mrow>}B1u$ state of symmetric tetrabromobenzens (s - TBB) in a durene host crystal at liquid helium temperatures. An analysis of the observed sturcture yields the two in-plane values of the bromine hyperfine tensor $|Ay/g\beta |=10.3$ and $|Az/g\beta |=16.5$ G (for $\mathrm{<mrow\; data-mjx-texclass="ORD">81</mrow>}Br$), and a comparison of these valus with those recently observed for the $\alpha$-bromomaleic acid radical suggests that the correct zero-field scheme in the lowest triplet state of s-TBB is $ T_{N}>T_{M}>T_{L}$.