Skeletal muscle relaxants are the medications used to relax and reduce tension in muscles. They act peripherally at neuromuscular junction/muscle fibre itself or at central nervous system to reduce muscle tone and/or cause paralysis. Neuromuscular junction consists of two components: nerve terminal, which forms the pre-synaptic structure, and muscle terminal, which forms the post-synaptic region. In between the two, lies the synaptic cleft. While synaptic cleft is the area between pre-synaptic and post-synaptic membranes, post-synaptic region is formed by muscle terminal. The chapter also covers acetylcholine receptor sub-units (alpha, beta, delta, epsilon, and gamma), peripherally acting muscle relaxants, centrally acting muscle relaxants, succinylcholine, atypical pseudocholinesterase, non-depolarising muscle relaxants (NDMRs), drugs like cisatracurium, mivacurium and sugammadex, critical illness myopathy, and general considerations in the use of muscle relaxants. NDMRs are the drugs that compete with acetylcholine for binding with alpha sub-unit of nicotinic receptors present at neuromuscular junction. Its classification, pharmacokinetics and side effects are also briefly described.