The performance and nutrient retention of broilers fed raw (RMD), toasted (TMD), boiled (BMD), soaked and boiled (SMD) or no (NMD) Mucuna cochinchinensis seed diets at both starter and finisher phases were assessed using 400 broiler chicks. The birds were fed a common proprietary feed (Top Feed) until 2 weeks of age, followed by a treatment diet for 3 weeks of the starter period, then 5 weeks on the finisher diet. At the starter phase, RMD significantly (P < 0.05) decreased liveweight, daily weight gain, protein efficiency ratio and encouraged poorer feed conversion ratio and higher cost per kilogram weight gain when compared with other diets. TMD decreased (P < 0.05) only the protein efficiency ratio. RMD also decreased (P < 0.05) retention of dry matter (DM), crude protein (CP), crude fibre (CF) and energy while TMD decreased (P < 0.05) retention of only DM, CP, and energy. At the finisher phase, RMD also significantly (P < 0.05) decreased daily weight gain, protein efficiency ratio and feed conversion ratio and increased cost per kg weight gain, while TMD decreased (P < 0.05) only the protein efficiency ratio and feed conversion ratio. RMD again decreased (P < 0.05) retention of DM, CP, CF and energy, while TMD, as in the starter phase, again decreased (P < 0.05) retention of DM, CP and energy. On a cumulative basis, RMD adversely affected (P < 0.05) all the parameters under investigation. TMD affected (P < 0.05) only the feed conversion ratio, protein efficiency ratio and cost per kg weight gain. Boiling Mucuna cochinchinensis, therefore, encourages significantly better performance of chicks, higher nutrient retention and lower cost per kg weight gain than toasting, whereas soaking before boiling does not add any advantage to boiling alone.