This report, funded by the UK Medical Research Council (MRC), is intended to inform the MRC by proposing and appraising two options for reviewing Units: Option A: Scientific track record, reviewed via site visits over variable time scales. Overall Unit synergy is assessed, with award of funding envelope allocated to research groups by Director. Option B: Future scientific strategy is assessed using Strategic Audits, metrics and Directors’ science strategy. Site visit is optional and determined by Quinquennial Review Subcommittee. Units will only supported if there is a strategic need. The two options have been developed through a series of consultations with the key stakeholders involved in the Unit Review process. The options are not proposals nor are they mutually exclusive; it is likely that elements of each are combined to produce a preferred model. Strengths and weaknesses of the two options were appraised, using an appraisal framework looking at their suitability, feasibility and acceptability. Finally, it is suggested how the two options respond to 25 key questions. It is stressed that these choices are best made by the MRC with wider interests to consider and balance.