The incident occurred around 2.30am in Rathowen.
Gardaí are appealing for witnesses following a crash in Westmeath overnight.
Shortly after 2:30am, Gardaí and emergency services responded to reports of a collision involving a car in Rathowen Village.
The two men, both in their 20s, were transported to Tullamore Hospital with serious injuries.
The scene is currently preserved for examination by Garda Forensic Collision Investigators and the N4 at Rathowen Village is currently closed to traffic.
Diversions are in place and will affecting those travelling between Mullingar and Longford.
Motorists are advised to plan their journeys accordingly.
Gardaí are appealing to anyone who may have witnessed this collision to come forward.
Road users who may have camera footage (including dash-cam) and were travelling on the N4 near Rathowen Village at the time of the collision are asked to make this footage available to investigating Gardaí.
Anyone with information is asked to contact Mullingar Garda Station at 044 938 4000, the Garda Confidential Line at 1800 666 111, or any Garda Station.
Westmeath Man Named Supreme Milk Quality Champion
Offaly Councillor Sees "Great Potential" For Village
Legislation Providing Paid Leave For Early Pregnancy Loss To Go To Cabinet
Offaly Councillor Seeks More Roads Funding In North Of County
Revenue Seize Contraband Worth Over €153k
Plans Lodged For New 24-Hour Automated Car Wash in Laois
Westmeath School Joins Expanded Online Admissions System
Offaly Soccer Club Seeks Green Light For Major Facilities Expansion
Laois Senator Warns Midlands STEM Progress At Risk Without New Funding
Offaly ICSA Sheep Chair Hits Out At Factories Over Lamb Prices
Calls For New Affordable Housing Strategy In Offaly
"Every Parent's Worst Nightmare" - Three Westmeath People Die In Malaga Crash
Offaly Community Group Points Finger At Renewable Energy Operators Over Road Damage
Defence Forces To Carry Out Training Exercise In Offaly
Gardai Ask Public For Help In Locating Missing Laois Teenager
Midlands School Raises Over €20k To Support Education In Uganda
Hauliers Call For Incremental End To Fuel Price Supports
Two Laois Designers Selected For National Design & Craft Gallery Exhibition
Ireland Prepares For EU Presidency With Increased Security
Fatal Westmeath Helicopter Crash Caused By Failed Training Manoeuvre