The energy transfer pathways from the excited accessory bacteriochlorophylls (B*) within native and modified(pheophytin-exchanged) reaction centres isolated from Rhodobacter sphaeroides (RS601) have been investigatedby using the femtosecond pump-probe technique. For native RS601, B* decays with a time constant of 240 fs, followed by a partial recovery of the ground-state bleaching with a tiescale of about 2ps. In modified RS601 (Phe),.however, B* decays with a time constant of 800rs for magic angle (54.7°) polarization configuration. In additionto the general assumption of energy transfer pathway from B* to the special pair P, an alteative pathway forenergy transfer probably operates as well.