Bromocriptine, a D2 receptor agonist, has been widely used in tumoral and non-tumoral hyperprolactinemia, in reducing both plasma prolactin levels and in restoring fertility and/or menses in most patients. In this study a comparison between the injectable repeatable and the oral slow release formulations of bromocriptine (Parlodel LAR and Parlodel SRO) is reported, with respect to their effectiveness, tolerability and safety. Eleven patients with hyperprolactinemia, submitted to both treatments, were studied for a period of 1-24 months. Among the four patients with macroprolactinoma, three reached normoprolactinemia without complaining of side-effects, with both formulations, while the remaining patient became intolerant of the oral form after 1 year, and is presently being treated with the injectable formulation without presenting any side-effects. Among the five patients with microprolactinoma, two patients had a good response to both drugs; two patients did not reach normoprolactinemia with the injectable formulations, but a progressive decrease of prolactin levels was obtained with Parlodel SRO therapy, and the remaining patient was completely intolerant of the oral form without complaining of side-effects with Parlodel LAR. Two patients had non-tumoral hyperprolactinemia: one was intolerant of both drugs and one tolerated both formulations very well. In conclusion, Parlodel LAR and Parlodel SRO are very effective compounds in the medical treatment of hyperprolactinemic syndromes. The availability of these differing formulations improves the medical therapy, allowing a better choice of therapeutic regimen according to the effectiveness of, and tolerability to, the different drug formulations. In this way also, with poorly tolerant patients, it is possible to choose the better tolerated and more effective formulation of the drug.