Femtosecond stimulated Raman spectra of trans-stilbene (D0), its isotopomers D2, D10, D12, 13C2 and of cis-stilbene in hexane are measured in the ground (S0) and excited (S1) electronic states. The ground 13C2 and excited D12 spectra are presented for the first time; the excited cis-spectra differ substantially from previously published ones. S1 Raman bands of trans-stilbene are 20 cm−1 wide corresponding to ∼1 ps vibrational dephasing. For cis-stilbene the bands are broadened to 40 cm−1 reflecting a short excited-state lifetime of 0.3 ps, in agreement with transient absorption data. From a dynamic shift of the 1569 cm−1 band, pump-induced intramolecular cooling is estimated to be less than 20 K. Many S1 Raman lines are detected for the first time. Vibrational spectra are calculated at MP2/cc-pVTZ (for S0) and XMCQDPT2/cc-pVTZ (for S1) levels of theory. Experimental and computational results can be used for a re-evalution of Rice-Ramsberger-Kassel-Marcus (RRKM) predictions for this famous photoisomeration reaction.