• We studied 55 patients admitted during 14 months to two inpatient psychiatric units of a municipal hospital who exhibited one or more of the catatonic signs of mutism, stereotypy, posturing, catalepsy, automatic obedience, negativism, echolalia/ echopraxia, or stupor. Only four of the 55 patients satisfied our research criteria for schizophrenia, whereas over two thirds had diagnosable affective disorders, usually mania. The eight catatonic motor signs were nonspecific and homogeneously distributed among the various research diagnostic groups, with the number and type of individual signs unrelated to short-term treatment outcome. A favorable treatment response was shown for the entire catatonic sample, with two thirds markedly improved or in remission at the time of discharge. These findings are consistent with those of other investigators of the catatonic syndrome for the past 100 years.