Haemolymph levels of amino acids, sugars and glycerol were investigated in the tenebrionid Stips stali during dehydration and rehydration. The absolute amount of amino acid decreases during dehydration and increases during rehydration, indicating active regulation of this solute (the osmolal contribution of amino acids is considerable). Glucose is the only sugar found in appreciable quantity in the haemolymph. Its osmolal contribution (and contribution to osmoregulation) is not great. Glycerol has a significant haemolymph osmotic presence, and changes in its levels contribute importantly to the regulation of haemolymph osmotic pressure. Ecological fitness of this species appears ensured by factors which include morphological, behavioural and physiological adaptations. Keywords: Osmoregulation, Stips stali Tenebrionidae, Namib Desert, amino acids, glucose, glycerol.