Purpose – The paper’s objectives are: to address the issue of cointegration (efficient market hypothesis) between Greek spot and futures markets over the period of the crisis, 1999-2001; to investigate the short-run and long-run efficiency of the FTSE/ASE-20 stock index futures contract and FTSE/ASE Mid 40 stock index futures contract traded on the Athens Derivatives Exchange(ADEX). Design/methodology/approach – This paper examines efficiency of the Greek stock index futures market from 1999 to 2001. A variety of econometric models are employed to test for cointegration between prices. The paper uses daily data from the Athens Stock Exchanges (ASEs) and the ADEX. A more detailed discussion on the causal relationship between spot and futures price in ADEX is obtained by using the impulse response functions of the vector error-correction model (to study the behaviour of series from real shocks). Findings – The results show that the Greek futures and spot prices form a stable long-run relationship. For both FTSE/ASE-20 and FTSE/ASE Mid 40, futures markets play a price discovery role, implying that futures prices contain useful information about spot prices. Futures markets are informationally more efficient than underlying stock markets in Greece. Practical implications – The results have important implications for both traders and speculators. The findings are strongly recommended to financial managers dealing with Greek stock index futures. Originality/value – The contribution of this paper is to provide evidence using data from the early stage of the ADEX (started its official operation on 27 August 1999). It also investigates whether the hypotheses exist after the dramatic rise of ASE stock prices.