Abstract. We present a clausal connection calculus for first-order intuitionistic logic. It extends the classical connection calculus by adding prefixes that encode the characteristics of intuitionistic logic. Our calculus is based on a clausal matrix characterisation for intuitionistic logic, which we prove correct and complete. The calculus was implemented by extending the classical prover leanCoP. We present some details of the implementation, called ileanCoP, and experimental results.