A carbon paste electrode was modified with β-cyclodextrin (β-CD/CPE) and used in the competitive voltammetric determination of antiviral drug, amantadine. Ferrocene (FC) was used as the electrochemical probe which competed with amantadine for β-CD cavity. Study of the complexation of FC and amantadine with β-cyclodextrin was followed by cyclic voltammetry. Inclusion of FC in β-CD cavity at the surface of the modified electrode showed the adsorptive nature of current flow $$ \left( {\Delta E_{\text{p}} \sim 0\;{\text{V}}} \right) $$ . The formation constant of FC–β-CD complex was calculated from voltammetric data to be 2.03 × 103 M−1. In the presence of amantadine, the adsorptive current of FC decreased. The stability constant of amantadine–β-CD complex was calculated to be 9.40 × 103 M−1. A linear relationship between current decrease and amantadine concentration was observed in the range of 0.1–1.0 mM using differential pulse voltammetry. The limit of detection was 0.08 mM with a sensitivity of 1.34 μA/mM. The modified electrode was used successfully in the determination of amantadine in tablets (recovery % = 96 ± 1 %).