Boss 1:Mara Aramov

be carefull to avoid the trains comming at you.Equip your M-16(do NOT use grenades)and start chassing Aramov.She's wearing a Flak Jacket so aim for her head.Once you get her, she won't die but you don't care, MISSION ACOMPLISHED

Boss 2:Anton Girdeux(me!!)

O.K. I'll give you my weak point.Avoid the fire and aim at the fuel container on my back.Use the shotgun.

Boss 3:Helicopter

This is a tough one!
Take the PK-102 and target the chopper.Start shooting and run for your life.Sometimes, bad guys start dropping from the chopper:kill them as they pose a serious threat to your survival.Continue shooting,the chopper will eventually crash.

Final Boss:Rohemer

Grab the gas grenades and throw one at Rohemer while avoiding his grenades.Guess what,YOU JUST SAVED THE WORLD!!
Now,start playing SF2.
Ps:watch the ending cinema until the end,you'll see it's not finnished.

videogames.com's walkthrough for syphon filter