Dendrimers are one of the most useful drug/gene delivery systems. Their ability to be internalized and transfect cells without inducing toxicity and be tuned for stimuli-induced delivery confers a great advantage over other carriers namely viral vectors. Despite most of preclinical reports dealing with dendrimeric drug delivery systems have shown promising data, there is the need, however, to intensify the comprehensive research (in vitro and in vivo) for elucidating their stimuli-responsiveness, biodegradability, biocompatibility, biodistribution, and bioelimination. Future looks bright for dendrimer-based technologies in theranostics especially in cancer. Dendrimers as synthetic enzyme mimics are also most promising in tissue engineering applications and catalysis. Other interesting applications include their use as photoluminescent, photoelectric, and nonlinear optic materials.