This naturalistic, observational pan-European study assessed the safety and early effectiveness of intramuscular (IM) psychotropic treatments in patients with acute agitation suffering from schizophrenia or bipolar mania. One thousand nine hundred and forty of 1945 patients completed the 24-hour observation period after initial IM treatment. Patients from 12 European countries were included (mean age 39 years; 58% male, 66% schizophrenia). IM treatment was at the physician's discretion. The primary objective was to describe the acute tolerability of IM psychotropic therapies in clinical practice, with particular emphasis on EPS. At baseline, 68% of the patients received IM monotherapy, with IM olanzapine most commonly prescribed (36%). During the first 24hours, 190 (9.8%) patients experienced EPS. The occurrence of EPS was statistically significantly lower in patients treated with IM olanzapine compared to those treated with other IM psychotropic medications (mainly typical antipsychotics and benzodiazepines): acute dystonia: 1.1%, 95% CI 0.5–2.3 and 2.9%, CI 2.0–4.0; akathisia: 2.3%, CI 1.3–3.7 and 5.5%, CI 4.3–6.9; Parkinsonism: 2.9%, CI 1.8–4.4 and 7.8%, CI 6.4–9.4, respectively. Anticholinergic treatment was given to 12% IM olanzapine versus 31% non-olanzapine treated patients. Acute agitation after 24hours was reduced by 1.68 (95% CI 1.46–1.91) points on the Clinical Global Impression of Severity (CGI-S) in IM olanzapine patients and 1.51 (95% CI 1.30–1.73) points in non-olanzapine patients. Additional psychotropic medication was required for 90% of the patients during the first 24hours of treatment. Results provide naturalistic evidence for low EPS rates and improvement of agitation with IM psychotropic medications during acute states of patients suffering from acute mania or schizophrenia.