Pulmonary surfactant is synthesised in alveolar type II cells and secreted in response to deep breathing (cell stretch), temperature changes and local biochemical factors, which include signals from the sympathetic (adrenergic) and parasympathetic (cholinergic) branches of the autonomic nervous system. Using a radiolabelled precursor (³H-choline) of surfactant, this study examines the thermal and neural control of surfactant secretion by type II cells isolated from a small heterothermic marsupial, Sminthopsis crassicaudata (fat-tailed dunnart). Both adrenergic and cholinergic agonists stimulated secretion at warm (37°C) and cold (18°C) incubation temperatures. Incubation with isoproterenol (adrenergic agonist), for two hours, significantly increased the proportion of incorporated ³H-choline secreted into the cell culture medium from 9.5% (basal) to 10.5% at 37°C (p = 0.02) and from 6.9% (basal) to 7.5% at 18°C (p = 0.03). The cholinergic agonist, carbamylcholine chloride also increased secretion from 9.6% to 11.9% at 37°C (p = 0.02) and from 6.9% to 7.4% at 18°C (p = 0.01). Temperature did affect the rate of secretion from type II cells (e.g. basal secretion was 9.6% at 37°C c.f. 6.9% at 18°C, p = 0.02), but the change in secretory rate between 37 and 18°C was less than expected if due to temperature alone (Q₁₀ = 1.3). The surfactant secretory pathway is therefore modulated by other factors, in addition to temperature. The response of type II cells to agonists remained the same at warm and cold incubation temperatures. For example, after two hours, adrenergic-stimulated secretion was 116.2% and 115.7% of basal secretion at 37°C and 18°C, respectively, p = 0.68. Therefore, a switch between adrenergic and cholinergic stimulation during torpor in dunnarts must only occur at a physiological level, and not also at the cellular level, as in lizards. Basal secretion was higher in dunnart type II cells than has been reported in rat type II cells and consequently, the agonist-stimulated increases in secretion from dunnart type II cells were much lower than observed for rat type II cells.