α,γ-Diaminobutyric acid (DAB), γ-N-oxalyl-α,γ-diaminobutyric acid (γ-ODAB), β-N-oxalyl-α, β-diaminopropionic acid (β-ODAP), homoserine (HS) and O-oxalylhomoserine (OHS) were isolated from the aerial parts of Lathyrus latifolius and their concentrations in the leaves, shoots and roots determined. Feeding experiments using larvae of Spodoptera littoralis indicated that γ-ODAB and OHS were antifeedants while β-ODAP and HS were phagostimulants over the concentration range used. DAB was a phagostimulant at low concentrations, but an antifeedant at higher concentrations.