Slowly polymerizing calcium alginate gels were investigated as a means of delivering large numbers of isolated chondrocytes by means of injection to determine if these gels would promote engraftment and could provide three-dimensional templates for new cartilage growth. Chondrocytes isolated from the articular surface of calf forelimbs were added to a 1 % sodium alginate dissolved in a 0.1 M potassium phosphate buffer solution (pH 7.4) to generate a final cellular density of 10 × 106/ml (representing approximately 10 percent of the cellular density of human juvenile articular cartilage). The calcium alginate-chondrocyte mixture was injected through a 22-gauge needle in 100-μl aliquots under the panniculus carnosus on the dorsum of nude mice and incubated for 6 (n = 4), 8 (n = 11), and 12 (n = 12) weeks in vivo. Time-zero specimens (n = 10) consisting of 100-μl aliquots of the calcium alginate-chondrocyte mixture were used to calculate initial weight. At harvest, all calcium alginate-chondrocyte specimens exhibited a pearly opalescence and were firm to palpation as early as 6 weeks after injection. By 12 weeks of in vivo incubation, the specimens weighed 0.15 ± 0.04 gm, significantly more than the initial weight of 0.11 ± 0.01 gm (p < 0.05). Specimens stained with hematoxylin and eosin demonstrated lacunae within a basophilic ground-glass substance. Control specimens of calcium alginate without chondrocytes (n = 4) had a doughy consistency 12 weeks after injection and had no histologie evidence of cartilage formation. This study demonstrates that an injectable calcium alginate matrix can provide a three-dimensional scaffold for the successful transplantation and engraftment of chondrocytes. This technique holds the promise of a minimally invasive means of delivering autogenous cartilage to correct or reconstruct facial contour deficiencies.