Abstract Study question What do Portuguese women know, and what attitudes do they reveal regarding fertility preservation? Summary answer There is a lack of knowledge concerning fertility preservation options and a solid desire to access more information. What is known already Fertility preservation techniques increase the possibility of conceiving a biological child later, whether for social or medical reasons, but it should be noted that they do not ensure success. Previous studies showed an insufficient knowledge of the population regarding cryopreservation techniques, their implications, and their benefits. Additionally, a high percentage of participants who do not consider using fertility preservation stated that it might be related to a lack of knowledge regarding fertility issues. It has been pointed out that people would like more information about fertility preservation and consider that reliable sources of information should be available to the public. Study design, size, duration Cross-sectional study. Participants' recruitment was set through online advertisement, using social media platforms and private messages, and participants were solicited to share the study link with two more women (Exponential Non-Discriminative Snowball Sampling method). The online advertisement comprised detailed information about the study’s aims and procedures, inclusion criteria, and the voluntary and anonymous nature of the participation. Data collection took place online between March and May 2022. Participants/materials, setting, methods 257 women aged 18-45. Participants completed a 9-items questionnaire. These questions addressed: a) knowledge concerning fertility preservation (e.g., Are you aware of the existence of any of the following fertility preservation options?); b) attitudes towards fertility preservation (e.g., Would you consider any of the following fertility preservation techniques?); and c) whether they would like to get more information on this topic (e.g., Would you like to receive more information about fertility preservation options?). Main results and the role of chance Eighty-eight (34.2%) participants were aware of the oocytes and embryos cryopreservation techniques, 60(23.3%) only knew the oocytes cryopreservation, 58(22.6%) were aware of oocytes, embryos, and ovarian tissue cryopreservation, 37(14.4%) did not know any of the previously mentioned techniques. Most women (n = 177; 68.9%) were not actively considering fertility preservation, 36(14.0%) would consider oocyte cryopreservation, 34(13.2%) would be willing to pursue it, but would need more information, 9(3.5%) would consider embryos cryopreservation and 1(0.4%) would consider ovarian tissue cryopreservation. Of those contemplating fertility preservation, 45(17.5%) would do it to prevent the effect of age on fertility, 21(8.2%) would do it due to the absence of a partner. Regarding the concerns about fertility preservation, the participants were worried about the costs (n = 26; 10.1%), age (n = 25; 9.7%), hormonal injections and other fertility drugs (n = 10; 3.9%) and the desire for spontaneous pregnancy (n = 8; 3.1%). The participants not considering preserving their fertility mentioned the main reasons were that they never thought about it (n = 56; 21.8%), did not want to get pregnant (n = 34; 13.2%), age (n = 32; 12.5%), the desire for spontaneous pregnancy (n = 28; 10.9%) and the costs (n = 16; 6.2%). Most participants agreed that fertility and fertility preservation information should be provided during medical consultations or at school. Limitations, reasons for caution The recruitment and data collection process (social media and online survey) have limitations, such as sampling bias, self-selection concerns, or under-representation of the population (e.g., exclusion of participants not using social media or online platforms), limiting the chance of making generalisations. Wider implications of the findings Making available more information regarding fertility preservation may warrant that more women have the opportunity to consider this option and make informed decisions regarding their reproductive life. Trial registration number not applicable