A range of still and sparkling mineral waters were assessed for their erosive potential together with comparator soft drinks using in vitro dissolution assays with extracted human teeth and powdered hydroxyapatite. Dissolution levels with all of the mineral waters were very low and for several still waters were undetectable. Sparkling mineral waters showed slightly greater dissolution than still waters, but levels remained low and were of the order of one hundred times less than the comparator soft drinks. De-gassing of a sparkling mineral water reduced its dissolution, but the total levels were still relatively low suggesting that carbonation of drinks may not be an important factor per se in respect of erosive potential. The complex and heterogeneous mineral compositions of mineral waters could influence the dissolution equilibrium of apatite in enamel and controlled addition of several ions to ultrapure deionized water was investigated. Calcium ions led to the greatest reduction in hydroxyapatite dissolution, but their effects were moderated by other ions including magnesium and sulphate. Thus, mineral waters appear to offer a safe alternative to more erosive acidic beverages and their complex mineral ion compositions may positively influence any dissolution processes at the tooth surface.