Summary This study presents an analytical method to determine double-porosity reservoir properties with interference pressure data in an infinite reservoir producing at constant pressure. Wellbore-storage and skin effects at production and observation wells are neglected. The effects of rD, λ, and ω on interference pressure responses are examined. For dimensionless interwell distances ≥ 100, the pressure responses are practically collapsed. As a result, a general type curve, which can be used for any value of rD, is presented that yields unique values of λ and ω for a given pressure response and rD. In addition to the log-log type curve, a semilog type curve that is more useful for pD values >0.1 is presented. Semilog derivatives of the interference pressure responses are considered. The pressure derivatives enhance small variations that occur in the pressure response during the flow period affected by the double-porosity nature of the reservoir. It is observed that for a simple correlation with λ and rD, the derivative curves for rD values > 100 can be collapsed. Hence, a semilog derivative type curve is developed. This type curve has two maxima. Early- and late-time behaviors are influenced by λ. The time separation between the first and second maxima is a function of ω.