The aim of the study was to evaluate the femoral cartilage thicknesses of hemiparetic patients after stroke using musculoskeletal ultrasonography and to determine whether there is any correlation between cartilage thicknesses and the clinical characteristics of the patients. Femoral cartilage thicknesses of both knees were measured in 87 (33 women, 54 men) hemiparetic patients. The mean age of the patients was 61.8 years (SD 11.1 years, range 32-87 years) and the mean duration of stroke was 12.3 months (SD 10.5 months, range 1-36 months). The outcome was measured in terms of motor recovery (Brunnstrom stages), spasticity (Modified Ashworth Scale), walking ability (Functional Ambulation Categories), and motor functioning (Functional Independence Measurement instrument). Ultrasonographic measurements were made axially from the suprapatellar window using linear probes while the patients' knees were held in maximum flexion. Three (midpoint) measurements were taken from both knees [lateral condyle (LFC), intercondylar area, and medial condyle (MFC)]. The mean cartilage thicknesses were found to be less on the paretic side (statistically significant only for LFC) when compared with the nonparetic side. Cartilage thickness values were found to be negatively correlated with the duration of immobilization (with paretic side LFC) and BMI (with both sides' MFC) and positively correlated with the Functional Independence Measurement motor score (with paretic side LFC) and the Functional Ambulation Categories scores (with both sides' LFC and MFC). Femoral cartilage is thinner on the paretic side in stroke patients. As the thickness values correlate with the duration of the disease and the ambulatory status of the patients, we suggest that early mobilization would be important in maintaining their cartilage integrity. (Contains 1 figure and 3 tables.)