A replicated field evaluation trial was conducted involving 13 accessions of Coleus forskohlii Briq. (Lamiaceae), a forskolin yielding aromatic herb with fasciculate tuberous roots. Forskolin (diterpenoid) is used for treatment of glaucoma, cardiomyopathy and certain cancers. Significant differences were recorded for all the characters except dry mass of roots. Maximum tuber number per plant (12.0) was in IIHR-59. Accession IIHR-59 also produced highest fresh and dry mass of tubers (870 g and 88.75 g, respectively) per plant. The harvest index was maximum (45.1%) in IIHR-80. The forskolin content was estimated using HPLC and was found to vary from 0.025 per cent (IIHR-1) to 0.798 per cent (IIHR-12). Forskolin yield per plant was highest in IIHR-7 (85.00 mg). The accession IIHR-80 with medium tuber yield and higher forskolin content (0.715%) can be promoted for commercial cultivation as the crop is propagated through vegetative means. INTRODUCTION Coleus forskohlii Briq. (Lamiaceae), a tuber bearing, perennial aromatic, Indian herb is an exclusive source of ‘forskolin’ (labdane diterpene). Forskolin is used in the preparation of drugs against glaucoma, congestive cardiomyopathy and certain cancers (deSouza et al., 1986). Apart from their medicinal uses, the tubers are also used as a condiment and pickled. C. forskohlii cultivars grown in India and those collected from wild exhibit a wide diversity in exomorphic and yield characters (Bahl and Tyagi, 1989). The forskolin content in tubers from wild sources is variable and large scale indiscriminate collection of this plant from its natural habitat has contributed to its enlistment as an endangered species (Vishwakarma et al., 1988). Therefore, collection, conservation, and evaluation of available diversity are of utmost important before the valuable genetic diversity is completely lost. In the present study, an evaluation of tuberous collections was undertaken for their tuber and forskolin yielding characters. MATERIALS AND METHODS The plant materials for the present study consisted of thirteen accessions originally collected from diverse regions of India. The experiment was laid out in a completely randomised design with three replications. Polybag rooted terminal shoot cuttings were used for planting. A spacing of 1 m x 1 m was adopted to avoid interplant competition. The roots were harvested 150 days after planting. Two randomly selected plants per replication were used for recording observations. Data on yield was recorded and analysed statistically using analysis of variance technique (Table 1). The forskolin estimation was carried out using HPLC technique as per the procedure described by Inamdar et al. (1984) with little modification. Chromatographic system: Waters HPLC Pump: Waters 575, binary gradient operated under isocratic conditions. Detector: Waters 2487 dual absorbance detector. Software: Millennium 32 chromatography software. Chromatographic conditions: (a) Mobile phase: HPLC acetonitrile grade: Millipore water (50 : 50) Proc. WOCMAP III, Vol. 1: Bioprospecting & Ethnopharmacology Eds. J. Bernath, E. Nemeth, L.E. Craker and Z.E.Gardner Acta Hort 675, ISHS 2005