There exist inflectional suffixes. For example, in English, the agreement morpheme <i>–s</i>, is a suffix, as in <i>John like-s Mary</i>. See Dryer (2008).
<br><br><b>Note:</b> Some languages have both inflectional prefixes and inflectional suffixes. These languages should be valued 'yes' for both properties. 
<br><br><b>Reference</b><br>
Dryer, Matthew S. 2008. Prefixing vs. Suffixing in Inflectional Morphology.
In Haspelmath et al. 2008, chapter 26.
Available online at <a href="http://wals.info/feature/26">http://wals.info/feature/26</a href>.