BACKGROUND: The present study was designed to (1) establish current sedation practice in UK critical care to inform evidence synthesis and potential future primary research and (2) to compare practice reported via a survey with actual practice assessed in a point prevalence study (PPS). METHODS: UK adult general critical care units were invited to participate in a survey of current sedation practice, and a representative sample of units was invited to participate in a PPS of sedation practice at the patient level. Survey responses were compared with PPS data where both were available. RESULTS: Survey responses were received from 214 (91 %) of 235 eligible critical care units. Of these respondents, 57 % reported having a written sedation protocol, 94 % having a policy of daily sedation holds and 94 % using a sedation scale to assess depth of sedation. In the PPS, across units reporting a policy of daily sedation holds, a median of 50 % (IQR 33-75 %) of sedated patients were considered for a sedation hold. A median of 88 % (IQR 63-100 %) of patients were assessed using the same sedation scale as reported in the survey. Both the survey and the PPS indicated propofol as the preferred sedative and alfentanil, fentanyl and morphine as the preferred analgesics. In most of the PPS units, all patients had received the unit's reported first-choice sedative (median across units 100 %, IQR 64-100 %), and a median of 80 % (IQR 67-100 %) of patients had received the unit's reported first-choice analgesic. Most units (83 %) reported in the survey that sedatives are usually administered in combination with analgesics. Across units that participated in the PPS, 69 % of patients had received a combination of agents - most frequently propofol combined with either alfentanil or fentanyl. CONCLUSIONS: Clinical practice reported in the national survey did not accurately reflect actual clinical practice at the patient level observed in the PPS. Employing a mixed methods approach provided a more complete picture of sedation practice in terms of breadth and depth of information.