This study investigates the impact of the Case-Based Learning (CBL) method for the topic of 'B6, B9 and B12 Vitamins' on students' academic achievement in a biochemistry course for an associate degree level in health. To this end, a case study with the title 'The Reasons for Depression: Do We Know What They Are?' was developed and implemented. The study had a one-group pre-test and post-test research design. The 'Vitamins' Achievement Test' (VAT) and a Structured Interview Form were used as data collection tools. First-year students of Medical Laboratory Techniques at the Ahmet Erdogan Vocational School of Health Services at Bulent Ecevit University (N = 34) who were aged between 18 and 20 made up the study group. The VAT and the Structured Interview Form were analysed using content analysis and the paired-samples t-test was used for the VAT. The results indicated that the frequency of students' responses in the 'clear understanding' category improved in the VAT post-test and it was concluded that there was a significant positive difference in the post-test scores of students. The results of the structured interview indicated that most of the students had positive opinions about the method, material and case study.