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Samples of 40 Macaca nemestrina and 12 Papio cynocephalus were tested for positive midfacial growth spurts. Relative growth rates were calculated for the sella-prosthion (S-Pr) and first incisor-first molar (P-M1) dimensions and trunk height using 6 observations between 2 and 7 years of age. Paired t-tests between chronologically adjacent rates revealed significant increases for S-Pr of male M. nemestrina but not for other comparisons. Individual growth rate curves for all three dimensions were examined to detect growth spurts of variable onset. The majority of male and female macaques and of male baboons showed positive growth spurts in S-Pr when individual rates were compared. The majority of both sexes of both species had growth spurts for trunk height. Growth spurts for P-M1 were most frequently absent in females of both species. Peak growth rates and growth rate increases were uniformly greater for males than females. S-Pr rate increases were more frequently present in conjunction with trunk height spurts than with P-M' growth accelerations. As with human samples, there exists a variable age of onset and duration of the midfacial growth spurt.