Increased fibroblast activity and collagen production have been observed frequently in proliferative scars. Previous studies have demonstrated that interferons suppress collagen production by means of normal, keloid, and hypertrophic scar‐derived fibroblasts. The fibroblast‐populated collagen lattice is an in vitro model used to study fibroblast function. We used fibroblast‐populated collagen lattices to evaluate the effect of interferon on fibroblasts harvested from normal human skin, human keloid, and hypertrophic scar tissues. Human recombinant interferon alfa‐2b (1000 IU/ml) was added to the culture media. The collagen gel, prepared from rat tail tendon bundles, was overlaid with 5 × 104fibroblast cells. Keloid fibroblast‐populated collagen lattices showed the highest contraction. Contraction in all the groups appeared suppressed by interferon alfa‐2b during the first 72 hours of study (p<0.05). The reduction in fibroblast‐populated collagen lattice contraction by interferon alfa‐2b was similar among the groups. The contractile properties of fibroblasts taken from normal human skin, keloids, and hypertrophic scars in this in vitro study were suppressed by interferon alfa‐2b. This suggested that interferon alfa‐2b may be beneficial for the treatment of