Abstract: Mature seeds of breadnut, cashewnut and fluted pumpkin were processed in the laboratory into the raw dried, boiled, fermented, germinated and roasted seeds. Differently processed seeds were dried at 50°C, ground and sieved through 500μm sieves. The seed flours were evaluated for trypsin inhibitor activity, tannin, phosphorus compounds and in vitro multienzyme protein digestibility (IVPD). The results show that processing significantly (P = 0.05) affected the antinutritional factors in the seed flours. Breadnut flours contain 2.8-5.3g/kg phytic acid, 5.8-9.2g/kg tannin and 0.9-8.1mg/g flour of trypsin inhibitor activity. Cashewnut flours contain 6.0-9.9g/kg phytic acid, 5.1-13.3g/kg tannin and 0.8-2.5mg/g flour of trypsin inhibitor activity. Fluted pumpkin seed flours contain 2.8-13.8g/kg phytic acid, 7.5-19.1g/kg tannin and 0.0-11.0mg/g flour of trypsin inhibitor activity. Fermentation is the most effective processing method to reduce phytic acid and trypsin inhibitor activity while boiling is most effective in reducing the tannin content. The result of IVPD of the seeds generally show that the boiled samples are the most digestible followed by the fermented samples while the raw dried/germinated samples are the least. The order of digestibility of the three seeds is fluted pumpkin (72.0 - 86.0%) > cashewnut (74.3 - 82.9%) > Breadnut flour (71.3 - 78.3%). Processing techniques used reduced the antinutritional factors in the seeds and improve its IVPD when compared with the raw dried seed flours.