Aggravation of risk and failure to take precautionary measures are focal issues in nonlife insurance in terms of potential partial or full release of the insurer from the duty to perform. Not infrequently, it is difficult to draw a line between the aggravation of risk on the one hand, and non-compliance with precautionary measures on the other, since a particular action by a policyholder may present both situations. At the same time, the legal remedies available to the insurer regarding these two situations are different in scope. The aggravation of risk and non-compliance with precautionary measures are precisely the bases on which insurers actually reduce indemnity or refuse to compensate for damages. This article explores the differences between insurance laws in the Baltic states—specifically, the Estonian Law of Obligations Act, the Latvian Insurance Contract Law and Lithuanian rules contained in the Civil Code and Insurance Law. The article explores the differences between the Baltic states’ insurance laws and the Principles of European Insurance Contract Law (PEICL) with regard to a policyholder’s duty in relation to aggravation of risk and precautionary measures, as the rights and obligations of policyholders do change where the optional instrument is applied. The article also includes comparisons to German, Finnish and Russian insurance law.