The effect of hyaluronate on chondrogenesis in cultures of chick limb-bud mesoderm cells, derived from stage 20--21, 23--24 and 26 embryos grown at different cell densities and in 3 different culture media, was studied. The results show that hyaluronate at a concentration of 500 microgram/ml, does not consistently produce an inhibition of chondrogenesis in cultures of stage 20--21, 23--24 or 26 limb-bud mesoderm cells in contrast to what has been reported by Toole et al. (1972). It was demonstrated that under optimal conditions, stage 26 cells grown in the absence of hyaluronate do not form as many cartilage colonies in culture as do cells from stage 20--21 or 23--24 embryos. It was determined that culture medium composed of Eagle's MEM supplemented with 7% horse serum, 3% fetal calf serum and 5% 10-day chick embryo extract supported chondrogenesis significantly better than Ham's F-12 supplemented with 10% fetal calf serum. Our results suggest that the inhibition of chondrogenesis by hyaluronate reported earlier is most likely due to the sub-optimal conditions of growth medium, cell density and embryonic stage than to the hyaluronate treatment.