Forensic analysis of drugs in hair using various modern instrumental analysis involves the use of different analytical techniques to detect, identify drugs and their metabolites that may be present in the hair. Forensic analysis of drugs from hair using instrumental analysis is a valuable tool for law enforcement agencies, workplaces, and drug treatment programs also in suspicious death due to poisoning, drug overdose, and doping in sports. Hair provides various advantages over urine and blood, such as easy sample collection and has the ability for providing retrospective drug intake or past history of drug abuse. Drug analysis in hair requires a smaller sample size, advancements in sample preparation techniques with lowered detection limits in instrumental analysis. Additionally, hair provides a chronological overview of the drug of abuse with reference to its micro-segmental analysis. This review paper aims to provide thorough understanding of the various instrumental techniques that are used to extract, isolate, identify the drugs and their metabolites based on their chemical and physical characteristics and their quantification in the hair. In majority of the cases, hair is not appreciated for its attributes as evidence. This paper tries to focus on the evidentiary value of hair and the techniques that are available globally