The Ph.D. program emphasizes cell and microbial biology. The purpose of the program is to prepare students for teaching, research, and administrative careers in biological or biomedical sciences. Courses in this program provide a foundation in biochemistry, cell biology, developmental biology, genetics, microbiology, molecular biology, neurobiology, and virology. In addition, presentations and participation in a graduate seminar program prepare students to be effective teachers and communicators. All graduate students accepted in the doctoral program are required to do some teaching during graduate training.

Standard prerequisites for graduate work in biology include two years of chemistry, two years of biology (including biochemistry and microbiology), one year of physics, and one year of calculus. Students admitted to the department with a deficiency take the required courses during the first year of graduate work. Applicants must include results of the Graduate Record Examination, preferably including an advanced test in one of the biological sciences.

There are two options for completion of the degree. In the first option (M.S./Ph.D.) the student first completes the M.S. degree before proceeding for the Ph.D. degree. The M.S. degree may be completed at Catholic University or at some other institution. In the second option (the direct Ph.D.) the student may proceed directly for the Ph.D. degree without obtaining the M.S. degree. The second option, which must be completed on a full-time basis until the written comprehensive examination is passed, is primarily intended for scientifically mature students who have had undergraduate research experience.

The curriculum for these two options is identical with two exceptions: 1) students in the direct Ph.D. option complete their written comprehensive examination during the fifth semester of studies; 2) students in the direct Ph.D. option must also complete one Research Problems course within the first three semesters of study in order for the faculty to evaluate their research potential. It is possible, however, for a student originally accepted into the M.S./Ph.D. option to request conversion to the direct Ph.D. program.

Students who have completed their M.S. at Catholic University and wish to enter the Ph.D. program should submit a letter stating their request to the Biology Graduate Admissions Committee for approval.