Background: Patient portals are online platforms that allow patients to view their medical records and test results. These portals can release patient’s medical test results immediately, negating fixed embargo periods before release; however, clinicians are concerned that without clinical guidance, via a face-to-face consultation, patients may misinterpret results, causing unnecessary distress or confusion. Objective: To explore patients’ views on delayed release of certain medical test results via a hospital patient portal, the acceptability of immediate access to test results, any concerns, and possible barriers or enablers to the roll-out of immediate access. Methods: A two-phase mixed method acceptability study, comprising: 1) a cross-sectional survey of portal users’ experiences of receiving medical test results and views on potential immediate access via the portal, and 2) semi-structured qualitative interviews exploring patients views on immediate access to test results in more depth. Results: 357 portal users completed the survey and 22 took part in interviews. Whilst most survey respondents favoured immediate access, interviews highlighted several potential issues this could cause, including avoidable distress and confusion in understanding results before clinician review. Conclusions: Immediate access to test results via the patient portal may only alleviate patient waiting anxiety in some cases. Clear, consistent information regarding procedures and timelines may be more appropriate in supporting patients to engage meaningfully in their healthcare.