Aftermarket may refer to:

• Aftermarket (merchandise), any market where customers who buy one product or service are likely to buy a related, follow-on product
• Aftermarket (automotive), the addition of non-factory parts, accessories and upgrades to a motor vehicle also to include removal of parts after vehicle is placed on market
• Aftermarket (finance), or secondary market in financial parlance, the trading of securities that have already been issued
• The market for parts that are no longer made, see new old stock