Abstract The mental gland of the plethodontid salamander Bolitoglossa nicefori was examined by macroscopic observation and light microscopy and compared with morphological descriptions of other species of Plethodontidae. The mental gland is an oval shaped pad which develops exclusively in reproductive males. It is composed of 255 to 710 simple glands of merocrine secretion arranged in a dorso-ventral disposition. The outlets of the glands are spindle-shaped or fusiform. Negative stain reaction for AB and PAS is consistent with results of the glandular components of mental glands from other Plethodontidae. Males of this species produce sperm continuously throughout the year: all examined adult males showed conspicuous mental glands. However, an evident and significant increase in the surface area of the mental gland pad, in the density of the glands, and in the number of tubular glands was observed in the males collected during the breeding season. At the histological level, a slight variation was observed among males in the height and diameter of the simple tubular glands, and significant variation was found in the diameter of the secretory granules. This variation may reflect the fact that, although males potentially can mate during all months of the year, females oviposit seasonally. During this defined season, the hypertrophy of the mental gland is the greatest.