Chlorinated or fluorinated alkenes undergo polymerization. Important halogenated polymers include polyvinyl chloride (PVC), and polytetrafluoroethene (PTFE, or teflon).
;Alkyl fluorides: An estimated one fifth of pharmaceuticals contain fluorine, including several of the top drugs. Most of these compounds are alkyl fluorides. Examples include 5-fluorouracil, flunitrazepam (Rohypnol), fluoxetine (Prozac), paroxetine (Paxil), ciprofloxacin (Cipro), mefloquine and fluconazole. Fluorine-substituted ethers are volatile anesthetics, including the commercial products methoxyflurane, enflurane, isoflurane, sevoflurane and desflurane.
;Alkyl chlorides: Some low molecular weight chlorinated hydrocarbons such as chloroform, dichloromethane, dichloroethene, and trichloroethane are useful solvents. Several million tons of chlorinated methanes are produced annually. Chloromethane is a precursor to chlorosilanes and silicones. Chlorodifluoromethane (CHClF) is used to make teflon.
;Alkyl bromides: Large scale applications of alkyl bromides exploit their toxicity, which also limits their usefulness. Methyl bromide is also an effective fumigant, but its production and use are controversial.
;Alkyl iodides: No large scale applications are known for alkyl iodides. Methyl iodide is a popular methylating agent in organic synthesis.
;Chlorofluorocarbons: Chlorofluorocarbons were used almost universally as refrigerants and propellants due to their relatively low toxicity and high heat of vaporization. Starting in the 1980s, as their contribution to ozone depletion became known, their use was increasingly restricted, and they have now largely been replaced by HFCs.