A new apparatus for the continuous cultivation of mono and mixed bacterial plaque on solid surfaces is described. The features are: (i) easy preparation and handling; (ii) freedom from technical problems and microbial contamination; (iii) self-sufficient for periods of up to 56 d; (iv) 12 samples are taken simultaneously; (v) programmable supply inlet. Experiments were performed with Streptococcus mutans C 67–1 for mono bacterial inoculation and in combination with Veillonella alcalescens V-1 for mixed bacterial inoculations. The results showed that the controlled conditions and versatility of the apparatus make possible the study of plaque-development and lesion production on a time-dependent basis. It is concluded that the apparatus is suitable for a wide range of dental and non-dental applications.