We describe a study conducted during 2009-12 into innovative assessment practice, evaluating an assessed coursework task on a final year Medical Genetics module for Biomedical Science undergraduates. An authentic e-assessment coursework task was developed, integrating objectively marked online questions with an online DNA sequence analysis tool (BLAST), routinely used by NHS and research professionals. The aim was to combine the assessment of understanding of complex module learning outcomes with real-world authentic skills highly valued in the work place. This approach challenges the oft-heard accusation that online computer-marked tests can lack validity and authenticity in higher education. The study demonstrates the content and construct validity of this form of e-assessment, showing that careful question design, allied with integration with the real life BLAST tool, enables instructors to assess complex higher order understanding, and requires students to demonstrate skills relevant for the work place. A study of three years of test results and measures of internal consistency data also show the reliability of this assessment. In addition, the results of surveys of student opinion and positive feedback from student module feedback questionnaires suggest that it is effective in terms of face validity.