We determined if the "relative age" effect, wherein older students in an age cohort in early grades do better academically, extends to birthdates of applicants to medical schools, and if birthdates are related to the success of their applications. We examined birthdays of applicants from Michigan to Wayne State University's School of Medicine, relative to December 1, the cut-off date for eligibility to enter kindergarten in Michigan. Significantly fewer applicants [less than or equal to] 22 years of age were born in the three-month period (September, October, November) immediately preceding the December 1 cut-off date, but there was no statistically significant difference in the probability of their acceptance. We conclude that delayed entry to kindergarten influences applications for medical school acceptance, but does not affect the success of their applications. (Contains 1 table.)