Two stages of progression have been described in malignant melanomas, namely, the so-called "radial" and "vertical" phases of growth. We sought the presence or absence of vertical growth in 211 invasive cutaneous malignant melanomas. Disease-free survival in 146 patients with vertical growth was 63.7%, whereas 100% of 65 patients whose neoplasms lacked this feature survived 5 years or more after ablation of their lesions without evidence of recurrence or metastasis. Microstaging of patients with malignant melanoma by traditional means (level of invasion and thickness) identifies groups of patients at low and high risk of metastasis. Our data suggest that the absence of vertical progression of growth identifies a group of patients whose risk of metastasis is close to zero.