every school except the uchicago considers you for the md pool if rejected from the md/phd route. at some schools (ucla, penn), the medical school never even interviews you at all, just the mstp committee; nevertheless, they can (and do) accept people to the medical school alone. this is slightly more nuanced, however. this very much depends on what type of applicant you were, and why you were rejcetyed from mstp. if you were too clinicall focused, then they may be more inclined to accept you md. if you would never have been acceptable for md-only, and mstp was your only in (some applicants are awesome, but fit this bill), it isn't likely that your app will be considered strongly.
the other aspect is that medschools are always concerned about their matric percentages - if you were rejected from the mstp but are still a good candidate and are committeed to medical science, very few school will bother giving you an md slot because they think you'll go somewhere else. only a few places have the confidence to think you will accept their md over other mstp's.
at most schools, if you are rejected pre-interview for mstp, you can explictly tell them you are interested in straight md (or they may ask directly). again, depends on what your app looks like.
the pre-mstp forum is rife with good info.
best,
-jot
