are you talking about healthcare specialties / concentrations in an MBA program? or a separate healthcare type program (such as the MHA or MPH) ?
if you are talking about an MBA degree with a focus on healthcare, most top business schools have concentrations in this field. i don't know what the rankings are for these programs, although anecdotally i have read that wharton and duke (fuqua) have 2 of the best healthcare specializations within their MBA programs.
a good way to start would be to go on a few of the top schools' websites, and browse their employment statistics for full time offers. look at quality of recruiters in this field (big pharma, hospitals, etc.) as well as placement stats. if a decent percentage of grads are choosing the pharma/healthcare field, with top pharma and biotech firms recruiting at the school - then this would indicate a fairly strong program.