Purpose: The purpose of this study was to determine the effectiveness of the microfracture technique in the treatment of full-thickness articular cartilage lesions of the knee. Methods: In this study the midterm results of 90 patients (47 women and 43 men) with focal full-thickness articular cartilage lesions who had been managed with the microfracture technique are presented. The mean age of our patients was 34.5 years (range, 20 to 58), and 51 right and 39 left knees were treated. All of the articular lesions involved medial femoral condyles. Results: On the basis of follow-Lip at a mean of 68 months (range, 24 to 108 months), mean improvements in Lysholm knee scores (from 54.2 to 84.6 points), Tegner activity scale scores (from 2.6 to 5.2 points), and Oxford knee interrogation scores (from 23,1 to 44.8 points) were observed (P < .0001). Moreover, there was a strong and significant correlation between functional results and age Younger than 35 years, size of defect less than 2 cm(2), non-weight-bearing surface, and body mass index lower than 25 kg/m(2), respectively (P < .001). Conclusions: According to our midterm results, the microfracture technique is quite effective with regard to the improvement of daily activities with a favorable impact on pain relief and better functional results. Furthermore, we found that there was a correlation between functional results and age, size of defect, location of defect, and body mass index as prognostic parameters. Level of Evidence: Level IV, therapeutic case series.