Allium sphaerocephalon subsp. sphaerocephalon, the common name is known as "Round-Headed Leek", is an edible plant in different countries. In the present study, bulb, stem and flower extracts of A. sphaerocephalon subsp. sphaerocephalon were compared in terms of phenolic profile and enzyme inhibitory activity, with A. sphaerocephalon subsp. trachypus which is not an edible species. Total phenolic and flavonoid contents of extracts were determined by spectrophotometrically, and bulb parts of both plants were found to be rich in phenolics. Twenty-four selected phenolic compounds were investigated qualitatively and quantitatively in the extracts by LC-MS-MS. Gallic acid (458.4-1246.4 mu g/g extract) as phenolic acid and 3-O-methyl quercetin (46.6-136.2 mu g/g extract) as a flavonoid were the major compounds in all extracts. In addition, enzyme (acetylcholinesterase (AChE), butyrylcholinesterase (BuChE) and tyrosinase) inhibitory potentials of all samples were performed using a 96-well microplate reader. Flower parts (IC50, 11.49 mu g/mL for AChE) and bulb parts of (IC50, 16.62 mu g/mL for BuChE, 65.94 mu g/mL for tyrosinase) A. sphaerocephalon subsp. sphaerocephalon were the most potent samples. Also, the results of all analyses were subjected to principal component analysis, to gain insight into the relationship between data of assays.