objectives: this retrospective study compared semen parameters from fertile men of two south american cities (medellín-colombia and petrópolis-brazil) to investigate their differences in some semen parameters. methods: we evaluated semen volume using a graduated tube, total progressive motility (a + b) using light microscopy (40x) and sperm concentration using a neubauer counting chamber. results: we observed that fertile men from medellín presented a significantly lower volume (p<0.0001), whereas individuals from petrópolis presented a significantly lower percentage of total progressive motility (p<0.0001). on the other hand, no difference was found in sperm concentration (p>0.05). conclusions: in conclusion, this study showed differences in semen parameters between fertile men of these south american populations. we think that these differences could be attributed to the geographical variations, like those observed in other countries. however, new studies are required to investigate this phenomenon and their causes.