Fixation may refer to:

• Carbon fixation, a biochemical process, usually driven by photosynthesis, whereby carbon dioxide is converted into organic compounds
• Fixation (alchemy), a process in the alchemical magnum opus
• Fixation (histology) in biochemistry, histology, cell biology and pathology, the technique of preserving a specimen for microscopic study
• Fixation (population genetics), the state when every individual in a population has the same allele at a particular locus
• Fixation (psychology), the state in which an individual becomes obsessed with an attachment to another human, an animal, or an inanimate object
• Fixation (surgical), an operative technique in orthopedics
• Fixation (visual) maintaining the gaze in a constant direction
• Fixation agent, a process chemical
• Fixation in Canadian copyright law, a concept in Canadian copyright law
• Nitrogen fixation, a process by which nitrogen is converted from its inert molecular form to a compound more readily available and useful to living organisms
• Session fixation, computer security attack
• Target fixation, attentional phenomenon
• “Fixation”, an episode of The Good Doctor