Hair analysis for illicit, recreational and therapeutic drugs though an evolving science is easier, less invasive of privacy and there is less chance of tampering with the sample to affect results. Often, a combination of capillary gas chromatography with mass spectrometry, though with known short comings, is preferred for detection of drugs in hair specimen. This study aimed at determination of chloroquine in the hair of mice by Ultra-Violet spectrophotometry. It has the advantage of being easy to operate and sensitive to trace amount. Twenty-five mice weighing about 25 g each were administered chloroquine phosphate intramuscularly once a week for 4 weeks. Hair was harvested from the same spot before, during administration and at the end of dosing. The samples of hair were extracted with methanol and the resultant residue dissolved in 0.1 M HCl. The resulting solutions were then run with the Ultra-Violet spectrophotometer to determine their concentrations using the calibration curve of the reference material. There was proportionate significant increase in the concentration of chloroquine phosphate in hair at the intervals of administration. The amount of chloroquine detected in hair samples increased from 2.98×10^-3/10 g of hair on the second week of administration to 4.88×10^-3/10 g of hair on the fourth week of administration. The result from the present study showed that although a new innovation, hair testing using Ultra-Violet spectrophotometry is a valuable has been seen as a valuable tool for drug analysis.