STUDY QUESTION Is it cost-effective to use in vitro fertilisation and preimplantation genetic testing of monogenic defects (IVT/PGT-M) to prevent transmission of BRCA1/2 mutations to second-generation new births in comparison with naturally conceived births? SUMMARY ANSWER In this cost-effectiveness analysis, we found that IVF/PGT-M is cost-effective for BRCA1 and BRCA2 mutation carriers if using a willingness to pay of $50 000 per quality-adjusted life-year (QALY). WHAT IS KNOWN ALREADY Carriers of a BRCA1 or BRCA2 mutation have a significantly increased risk of several types of cancer throughout their lifetime. The cost of risk reduction, screening and treatment of cancer in this population is high. In addition, there is a 50% chance of passing on this genetic mutation to each child. One option to avoid transmission of an inherited deleterious gene to one’s offspring involves in vitro fertilisation with preimplantation genetic testing. STUDY DESIGN, SIZE, DURATION We implemented a state transition model comparing the healthcare impact of a cohort of healthy children born after IVF/PGT-M, who have a population risk of developing cancer, to a cohort of naturally conceived live-births, half of whom are carriers of the BRCA mutation. Transition probabilities are based on published sources, a lifetime horizon and a perspective of a provincial Ministry of Health in Canada. PARTICIPANTS/MATERIALS, SETTING, METHODS The target population is the second-generation new births who have at least one parent with a known BRCA1 or BRCA2 mutation. MAIN RESULTS AND THE ROLE OF CHANCE At a willingness-to-pay threshold of $50 000 per QALY, IVF/PGT-M is a cost-effective intervention for carriers of either BRCA mutation. For BRCA1, the incremental cost-effectiveness ratio (ICER) for IVF/PGT-M is $14 242/QALY. For BRCA2, the ICER of intervention is $12 893/QALY. Probabilistic sensitivity analysis results show that IVF/PGT-M has a 98.4 and 97.3% chance of being cost-effective for BRCA1 and BRCA2 mutation carriers, respectively, at the $50 000/QALY threshold. LIMITATIONS, REASONS FOR CAUTION Our model did not include the short-term negative effect of IVF/PGT-M on the woman’s quality of life; in addition, our model did not consider any ethical issues related to post-implantation genetic testing. WIDER IMPLICATIONS OF THE FINDINGS In countries in which the healthcare of a large segment of the population is covered by a single payer system such as the government, it would be cost-effective for that payer to cover the cost of IVF/PGT-M for couples in which one member has a BRCA mutation, in order to avoid the future costs and disutility of managing offspring with an inherited BRCA mutation. STUDY FUNDING/COMPETING INTEREST(S) Dr Wong’s research program was supported by the Canadian Institutes of Health Research (CIHR), the Natural Sciences and Engineering Research Council (NSERC), the Canadian Liver Foundation and an Ontario Ministry of Research, Innovation and Science Early Researcher Award. All authors declared no conflict of interests.