This paper examines the effects of time to maturity, volume and open interest on the price volatility of futures contracts in Turkish derivative markets. The determinant of volatility is tested using conditional variance models during the period from January 2, 2008 to June 30, 2015. The sample set consists of 457 futures contracts backed by gold, currency, indices and single stocks. Empirical results show that the time to maturity, volume and open interest significantly impact the volatility of futures contracts. It is found that as the maturity date approaches, volatility increases. Furthermore, a positive correlation is found between the price volatility of futures contracts and volume, whereas volatility and open interest are found to correlate negatively. Thus, both the Samuelson Hypothesis and the Mixture of Distributions Hypothesis are supported in Turkish derivative markets.