Increasing the strength of the magnetic field is a tempting technical evolution, promising better signal-to-noise ratio and reduced acquisition time. The shift to ultra high field (3.0 Teslas and over) does have its pitfalls however and the physical consequences of increasing the field go beyond simply increasing the signal-to-noise ratio. It is useful to be aware of the advantages and limitations of ultra high fields to better apprehend the possibilities of the technique, which often involves making compromises - as is always the case in MRI!