Dorsal displaced distal radius fracture (Colles' fracture) is very common and could occur from fragility in middle-aged and elderly people. Many Colles' fractures are still treated conservatively in clinics without hospitalization. Internal fixation using a palmar locking plate has been the standard treatment, but some complications have been reported. The aim of this study was to analyze changes in radiographic parameters over time in patients with conservatively treated Colles' fractures, and to establish whether the type of fracture influenced these changes. Prospective data collected included patient characteristics and radiological findings. The study was conducted at two private clinics and included 60 patients (13 men and 47 women; mean age, 72.5 years old; range, 55 to 96 years old) with a Colles' fracture (types of injury: intramedullary [n = 15], anatomical [n = 39], extramedullary [n = 2], and unknown [n = 4]) who were treated conservatively with manipulation and cast immobilization. Conservative, nonsurgical treatment with manipulation was performed first, then, cast immobilization continued for 4 weeks. Loss of correction between the time of reduction and the final observation was defined by the following radiographic measurements: palmar tilt, radial inclination, and ulnar variance. The average final follow up period was 4.6 months (1.5-12 months). Immediately after reduction, 11 intramedullary fractures, 42 anatomical fractures and 7 extramedullary fractures were confirmed. Correction loss according to ulnar variance was significantly greater (P = 0.012) during the final observation for patients with an intramedullary injury at reduction than that for patients with extramedullary and anatomical injuries at reduction. We found that the correction loss for ulnar variance from immediately after reduction until the final observation was significantly greater in the intramedullary group, suggesting that an alternative to conservative treatment may be beneficial for patients with intramedullary fractures.