The aim of the study was to compare the short-term biocompatibility of grey mineral trioxide aggregate (GMTA), Retroplast and Geristore. Silicon tubes filled with the materials and empty control tubes were implanted in the dorsal connective tissue of 30 Wistar albino rats. The tubes and surrounding tissues were excised and prepared for histological examination at 1 week, 1 month and 2 months after implantation. Inflammatory cell counts and the presence or absence of necrosis adjacent to the materials and control tubes were recorded. Data were statistically analysed using one-way anova and Tukey's multiple comparisons tests. The empty control tubes were well tolerated. All tested materials showed a more severe initial reaction than the control group. With time, the reaction became chronic, with variable increase in the numbers of inflammatory cells. Retroplast recorded the most statistically significant increase in the sum of inflammatory cells. Although the increase in the sum of inflammatory cells was statistically significant for Geristore but not for GMTA, the inflammatory cell counts for both were comparable. It was concluded that the three materials continued to irritate tissues throughout the evaluation period. Retroplast was the least biocompatible of the three tested materials at 2 months, followed by Geristore then GMTA.