A study of the pharmacological properties of pyrrolo[2,1-c][1,4]benzodiazepine derivatives led to the choice of (+)-1,2,3,11a-tetrahydro-10-methyl-5H-pyrrolo[2,1-c][1,4]benzodiazepine-5,11(10H)-dione as a candidate for anxiolytic evaluation in a limited clinical trial in man. Metabolism studies in laboratory animals pointed to rapid hydroxylation, possibly in the 3 and 11a positions. A series of compounds containing methyl groups in 1 or more of these positions was prepared to block metabolism and thereby obtain more active or longer acting compounds. All of these derivatives were less active than the parent compound.