Objective: This study aimed to examine expenditure items and amounts and whether these expenditures constitute an economic burden for individuals with diseases requiring low-protein diets. The study also evaluates patients’ perceptions regarding the adequacy, affordability, and accessibility of dietary products. Methods: In this descriptive and cross-sectional study, 141 participants living in Türkiye were included in the sample. Most participants had Phenylketonuria (PKU), but individuals with diseases such as maple syrup urine disease, alkaptonuria, and homocystinuria were also included in the study. The study used a 28-question questionnaire form created by the researchers based on expert opinion. The research data collected between 29.09.2023 and 15.03.2024 were analyzed in the SPSS package program. Results: 84.4% of the study participants were patients with PKU. The study determined that 41.1% of the participants had physician and hospital service expenditures, 27% had expenditures on medicines and medical supplements, 95.7% had low protein food expenditures, and 31.2% had other expenditures (transportation, special education, etc.) other than these items. Most participants reported that the variety of products related to their diseases needs to be improved, product costs are high, and their expenditures on these products pose a challenge for their household budget. When the amounts of expenditures were analyzed, the average annual physician and hospital service expenditure was 636.84 ± 736.44 USD, the average expenditure on medicines and medical supplements was 610.44 ± 741.60 USD, the average low protein food expenditure was 1847.16 ± 1166.88 USD, and the average other expenditure was 764.64 ± 650.76 USD. When all expenditures are considered together, a patient spends an average of 2451.12 ± 1758.12 USD per year. Conclusion: The study demonstrates that annual out-of-pocket expenditures for patients with diseases requiring a low-protein nutrition are considerable, placing a substantial financial strain on affected households. If a household earning the national minimum wage had annual out-of-pocket expenditures at the sample mean, these would represent approximately 39% of their income.