Natural latex does not fall into the category of materials known to be entirely inoffensive. The objective of the present in vitro study is to test the hypothesis that there is no difference in the cytotoxicity between natural latex elastics of different colours. The present article compared different latex intra-oral elastics (5/16 = 7.9 mm). The sample was divided into four groups according to their manufacturer: Group N (Natural latex elastic, Morelli), Group R (Red colour elastic, Morelli) Group Y (Yellow colour elastic, Morelli) and Group G (Green colour elastic, Morelli). Cytotoxicity assays were performed by using cell culture medium containing L-929 line cells (mouse fibroblast). The cytotoxicity was evaluated by using the &#8220;dyeuptake&#8221; test, which was employed at two different moments (1 and 24 h). Data were compared by analysis of variance (ANOVA) and Tukey&#8217;s test (p<0.05). The results showed a significant difference (p<0.05) between the groups N, R, Y, G and the negative cytotoxicity control at 1 and 24 h (p<0.05), it did not have presented significant difference between the groups N, R, Y, G tested (p&gt;0.05) at 1 and 24 h. Morelli intra-oral elastics were found to be highly cytotoxic, regardless of their colour and immersion time.