In the absence of data on the dynamics of cementum apposition, one female Macaca fascicularis monkey, born July 1984 and sacrificed July 1985, was sequentially injected with calcein and xylenol orange 10 times, about every 33 days. Following fixation in formalin, the right and left maxillary and mandibular jaw segments were embedded in MMA and serially sectioned in the mesio-distal or bucco-oral directions, adapting the plane of sectioning to the various root axes. A total of 230 ground sections were produced. A selected set of sections then served for estimating the interval distances between the various lines of fluorescence and for calculating the daily rates of apposition of acellular and cellular cementum as well as of crown and root dentine of all deciduous and the first permanent molar teeth, using fluorescence microscopy and morphometric equipment. The resulting data were as follows: Acellular cementum formed at a rate of 0.10 +/- 0.02 microns/day, cellular cementum with initial rates of 0.4 to 3.1 and appositional rates of 0.1 to 0.5 microns/day. In comparison, crown dentine of the first permanent molar formed with a stable rate of about 3.1 microns/day, while the rate of root dentine formation varied from 4.6 to 2.7 microns/day in deciduous teeth, and from 2.2 to 3.2 microns/day in first permanent molars. Roots of deciduous teeth grew with an initial rate of 30 to 35 microns/day and this slowed down further apically to 10 to 14 microns/day. Roots of the first permanent molars formed with initial rates of 10 to 18 microns/day only.