Extraction of high-quality RNA is necessary for making cDNA libraries, isolating genes by RT-PCR, or investigating gene expression profiles. Several methods are commonly used for isolation of total RNA [1–3] and are being developed because plants contain high amounts of many different substances; therefore, just one nucleic acid isolation method suitable for all plants can never exist [4]. Even plant species belonging to the same genus or related genera can exhibit enormous variability in the complexity of pathways of dispensable functions. Thus, the biochemical compositions in plant tissues of different species are expected to vary considerably. The chemotypic heterogeneity among species may not allow optimal RNA yield from one isolation protocol and, perhaps, even closely related species may require different isolation protocols [5]. As our aim has been to study drought-induced differential expression of genes during early and late seed developmental stages in sorghum, we may need a protocol that not only can give the same quality and quantity of RNA at each stage but also is high yielding in order not to miss the rarely expressed genes. Previous standard plant RNA isolation procedures failed to work when applied to tissues rich in secondary products [3,6–8]. In this report, a procedure developed by Logemann et al. [3] was modified and applied to sorghum seeds, which are known to contain high levels of polysaccharides [9]. The extraction method described in this study is simple, not requiring ultracentrifugation or additional precipitation steps, and allows RNA extraction from plant species in which other procedures have previously been unsuccessful. Further, the quality of the isolated RNA was consistently high as indicated by spectrophotometric readings and its separation on denaturing agarose gels. The yield and quality were suitable for RT-PCR and Northern blot hybridization. Seeds of sorghum (Sorghum bicolor cv. CSH-6) were purchased from the National Seed Corp., (Pusa, New Delhi, India) and seeds of chickpea (Cicer arietinum), and soybean (Glycine max) were purchased from Punjab Agricultural University (Ludhiana, India). The seeds were surface sterilized with 1% (w/v) mercuric chloride and 70% ethanol followed by rinsing with deionized water. Seeds were imbibed for 6 h in doubledistilled water at 37 C and used for further studies. Leaves of soybean and chickpea were collected from 6day-old germinated seedlings grown in a seed germinater. Tissues were stored in liquid nitrogen for further analysis. Solutions and reagents used were as follows: homogenization solution (Solution I), NaCl (5M), Sarkosyl (2%); guanidine hydrochloride buffer (pH 7.0), 8M guanidine hydrochloride, 20mM EDTA, 20mM Mes, 50mM b-mercaptoethanol; phenol:chloroform:isoamyl alcohol (PCI) 25:24:1; chloroform:isoamyl alcohol (CI) 24:1; chilled absolute ethanol and 70% ethanol; 1M acetic acid; 3M sodium acetate (pH 5.3); 0.2% DEPC-treated autoclaved double-distilled water. Glassware and plasticware used were as follows: glassware and mortar pestles (baked overnight at 180 C), pipette tips (DEPC treated and autoclaved), gel running apparatus (treated with 3% H2O2 and incubated overnight with DEPC-treated water), 50-ml polypropylene centrifuge tubes (washed and incubated overnight at room temperature with DEPC-treated water). The RNA extraction protocol is as follows. • Grind the tissue to a fine powder (0.5–1.0 g) with the help of pestle and mortar. Analytical Biochemistry 314 (2003) 319–321