Different crystal forms diffracting to high resolution have been obtained for two NADP(H)-dependent alcohol dehydrogenases, members of the medium-chain dehydrogenase/reductase superfamily: ScADHVI from Saccharomyces cerevisiae and ADH8 from Rana perezi. ScADHVI is a broad-specificity enzyme, with a sequence identity lower than 25% with respect to all other ADHs of known structure. The best crystals of ScADHVI diffracted beyond 2.8 Å resolution and belonged to the trigonal space group P3121 (or to its enantiomorph P3221), with unit-cell parameters a = b = 102.2, c = 149.7 Å, γ = 120°. These crystals were produced by the hanging-drop vapour-diffusion method using ammonium sulfate as precipitant. Packing considerations together with the self-rotation function and the native Patterson map seem to indicate the presence of only one subunit per asymmetric unit, with a volume solvent content of about 80%. ADH8 from R. perezi is the only NADP(H)-dependent ADH from vertebrates characterized to date. Crystals of ADH8 obtained both in the absence and in the presence of NADP+ using polyethylene glycol and lithium sulfate as precipitants diffracted to 2.2 and 1.8 Å, respectively, using synchrotron radiation. These crystals were isomorphous, space group C2, with approximate unit-cell parameters a = 122, b = 79, c = 91 Å, β = 113° and contain one dimer per asymmetric unit, with a volume solvent content of about 50%.