A resealable cap (110, 210) for a medicament vial (114, 214) has a base portion (112, 212) formed of vulcanized rubber or like material known for providing a stable environment for the medicament contained within the vial, and a resealable portion (126, 226) overlying the base portion. The resealable portion (126, 226) is made of low-density polyethylene or like material, and can be punctured by a needle or like injection member (140, 282) for dispensing medicament into the vial (114, 214). Prior to filling, the cap (110, 210) is assembled to the vial (114, 214) and the cap/vial assembly is sterilized. Then, a needle (140, 282) is inserted through the cap (110, 210) and medicament is introduced through the needle and into the vial. Upon withdrawal of the needle (140, 282), the penetrated region of the cap (248) is fused by laser (276) or direct heat sealing (264) to hermetically seal the needle hole (294) in the cap.