can MTA Metrocards be used on the Metro-North train lines?

Unfortunately no.

Though what I think what the MTA SHOULD do is that when you purchase a ticket through the machine, if you have a regular Metrocard (not one with the day or month passes), you can insert that in and the fare would be deducted from it. That would work out well for those that use TransitChek that do use regular transit but once in a blue moon may need to go on Metro-North or LIRR.

Metro North Train Pass

ajedrez has wrong information for Bee-Line Bus routes. Do not take #4, 1C, #5 or #6. They do not go near Hartsdale Station. Sorry, MTA MetroCard are not accepted on Metro-North Railroad, however you could use your MetroCard on Bee-Line buses in Westchester County. Metro-North weekly ticket cost you $73.25. Hartsdale Station on Hartsdale Av-Fenimore Rd by Bronx River Parkway You could take uptown (4) train to Bedford Park Blvd station for Bee-Line #20 which stops at Central Park Av/Hartsdale Av SE corner. Once you get of make right at Hartsdale Av and walk about 6 blocks toward Hartsdale Station. During PM Rush Hour, you could transfer from Bee-Line 20 to Bee-Line #34 #38 #39 going to Hartsdale Station at Central Park Av/Hartsdale Av.

No, Metro-North and Long Island Railroads are commuter rail in NY, upstate NY and Connecticut. They're based on fare zone similar to New Jersey Transit trains and buses.

However Metro-North and Long Island Railroad ticket vending machine in NYC, Westchester and Nassau County sell $20 MetroCard or $5 MetroCard for Airtrain JFK).

Also, Mail & Ride give you Monthly Pass based on your fare zone and it includes Monthly MetroCard for unlimited ride on NYCT, MTA Bus, Long Island Bus and Bee-Line local buses, Subways and Staten Island Railway.

However, MetroCards are accepted on Westchester County Bee-Line Buses and NYC Buses, well as Long Island Bus.

If you prefer to use MetroCard, only Westchester County Bee-Line is your option.

no, because there are no turnstiles you have to go through to enter a Metro North station, you just get on the train. you'll have to buy a Metro North ticket.

no, the metro north ticket is different

not the trains but the bee line busses