Aim:To find an in vitro system for the measurement of the androgenic effects of different extracts of Hibiscusmacranthus(Malvaceae)and Basella alba(Basellaceae).Methods:The production of testosterone from testes slicesincubated in two media,either Krebs-Henseleit buffer containing 0.5 % Bovine serum albumin(BSA)or Dubecco’sModified Eagle’s medium-F12 Ham nutrient mixture(DME/Ham F12),under a mixture of 5 % CO_2 in 95% air wasdetermined either in the presence or absence of cofactors and Hibiscus macranthus plus Basella alba(HMBA)extracts.Results:The testosterone production was increased in testes slices incubated in DME/Ham F12 medium inresponse to the cofactors(49%)and aqueous extracts(34%-60% according to dilutions).Under the same atmo-spheric conditions,there was no positive response of the testes slices to either cofactor or HMBA extract stimulationin Krebs-Henseleit buffer containing 0.5% BSA.In further investigations related to the effect of HMBA,the DME/Ham F12 medium was used.The results obtained from the in vitro test showed that the activity was present mainlyin methylene chloride and methanol,since these extracts induced an increase in testosterone production by testesslices.Conclusion:The testes slice system is suitable to be used for further in vitro investigations of the isolation ofandrogenic bioactive components of plants.(Asian J Androl 2006 Jan;8:111-114) Aim: To find an in vitro system for the measurement of the androgenic effects of different extracts of Hibiscus macranthus (Malvaceae) and Basella alba (Basellaceae). Methods: The production of testosterone from testes slicesincubated in two media, either Krebs-Henseleit buffer containing 0.5 % Bovine serum albumin (BSA) or Dubecco’s Modified Eagle’s medium-F12 Ham nutrient mixture (DME / Ham F12) under a mixture of 5% CO 2 in 95% air was determined either in the presence or absence of cofactors and Hibiscus macranthus plus Basella alba (HMBA) extracts.Results: The testosterone production was increased in testes slices incubated in DME / Ham F12 medium inresponse to cofactors (49%) and aqueous extracts (34% -60% according to dilutions) .Under the same atmo- spheric conditions, there was no positive response of the testes slices to either cofactor or HMBA extract stimulationin Krebs-Henseleit buffer containing 0.5% BSA. Further investigations related to the effect of HMBA, the DME / Ham F12 medium was used.Th e results obtained from the in vitro test showed that the activity was present mainly methylene chloride and methanol, since these extracts induced an increase in testosterone production by testesslices. Conlusion: The testes slice system is suitable to be used for further in vitro investigations of the isolation of androgenic bioactive components of plants. (Asian J Androl 2006 Jan; 8: 111-114)