Eccrine sweat glands (; from Greek ekkrinein 'secrete'; sometimes called merocrine glands) are the major sweat glands of the human body, found in virtually all skin, with the highest density in palm and soles, then on the head, but much less on the torso and the extremities. In other mammals, they are relatively sparse, being found mainly on hairless areas such as foot pads. They reach their peak of development in humans, where they may number 200–400/cm² of skin surface. They produce a clear, odorless substance, sweat, consisting primarily of water. These are present from birth. Their secretory part is present deep inside the dermis.

Eccrine glands are composed of an intraepidermal spiral duct, the "acrosyringium"; a dermal duct, consisting of a straight and coiled portion; and a secretory tubule, coiled deep in the dermis or hypodermis. The eccrine gland opens out through the sweat pore. The coiled portion is formed by two concentric layers of columnar or cuboidal epithelial cells. The epithelial cells are interposed by the myoepithelial cells. Myoepithelial cells support the secretory epithelial cells. The duct of eccrine gland is formed by two layers of cuboidal epithelial cells.

Eccrine glands are active in thermoregulation by providing cooling from water evaporation of sweat secreted by the glands on the body surface and emotionally induced sweating (anxiety, fear, stress, and pain). The white sediment in otherwise colorless eccrine secretions is caused by evaporation that increases the concentration of salts.

The odor from sweat is due to bacterial activity on the secretions of the apocrine sweat glands, a distinctly different type of sweat gland found in human skin.

Eccrine glands are innervated only by the sympathetic nervous system. Postganglionic sympathetic fibers innervating the cutaneous district can produce either noradrenaline or acetylcholine as neurotransmitters depending on the target structure. The sympathetic cholinergic fibers connecting with the sweat glands discharge primarily by changes in deep body temperature (core temperature). The glands on palms and soles do not respond only to temperature stimuli but secrete at times of emotional stress.