English contract law has traditionally taken the view that it is not the duty of the parties to a contract to give information voluntarily to each other. In English law, one of the principal distinctions between insurance contract law and general contract law is the existence of the doctrine of utmost good faith in insurance law. The doctrine gives rise to a variety of duties, some of which apply before formation of the contract while others apply post-formation. This article is, therefore, designed to analyse the overall structure and problems of the doctrine of utmost good faith in English marine insurance law. The results of analysis are as following : First, the requirement of utmost good faith in marine insurance law arises from the fact that many of the relevant circumstances are within the exclusive knowledge of the assured and it is impossible for the insurer to obtain the facts to make a appropriate calculation of the risk that he is asked to assume without this information. Secondly, the duty of utmost good faith provided in MIA 1906, s. 17 has the nature as a bilateral or reciprocal, overriding and absolute duty. Thirdly, the Court of Appeal in Skandia held that breach of the pre-formation duty of utmost good faith did not sound in damages since the duty did not arise out of an implied contractual term and the breach did not constitute a tort. Instead, the Court of Appeal held that the duty was an extra-contractual duty imposed by law in the form of a contingent condition precedent to the enforceability of the contract. Fourthly, the scope of the duty of utmost good faith is closely related to the test of materiality and the assured is required to disclose only material circumstances subject to MIA 1906, s. 18(1) and 20(1). The test of materiality, which had caused a great deal of debate in English courts over 30 years, was finally settled by the House of Lords in Pan Atlantic and the House of Lords rejected the 'decisive influence' test and the 'increased risk' test, and the decision of the House of Lords is thought to accept the 'mere influence' test in subsequent case by the Court of Appeal. Fifthly, the insurer is, in order to avoid contract, required to provide proof that he is induced to enter into the contract by reason of the non-disclosure or misrepresentation of the assured. Sixthly, the duty of utmost good faith is, in principle, terminated before contract is concluded, but it is undoubtful that the provision under MIA 1906, s. 17 is wide enough to include the post-formation duty. The post-formation duty is, however, based upon the terms of marine insurance contract, and the duty lies entirely outside s. 17. Finally, MIA 1906, s. 17 provides expressly for the remedy of avoidance of the contract for breach of the duty. This means rescission or retrospective avoidance of the entire contract, and the remedy is based upon a fairly crude 'all-or-nothing' approach. What is needed in English marine insurance law is to introduce a more sophiscated or proportionate remedy.