Background/Aim. Bone bruise is a common finding in acutely injured knee examined by magnetic resonance (MR). The aim of the study was to determine the association of bone bruise frequency with postinjury lesions of anterior cruciate ligament (ACL) and menisci. Bone bruise involves posttraumatic bone marrow change with hemorrhages, edema and microtrabecular fractures without disruption of adjacent cortices or articular cartilage. MR imaging is a method of choice for detecting bone bruises which can not be seen on conventional radiographic techniques. Methods. A representative review of 120 MR examinations for the acute knee trauma was conducted. All the patients were examined within one month of trauma. All MR examinations were performed by using a 0.3T MR unit. Results. Posttraumatic bone bruise was seen in 39 (32.5%) patients out of 120. Three patients had fracture of the cortex, so-called “occult” fracture (not seen on plain radiography). We analyzed only bone bruises without these fractures of the cortex. Bone bruise was associated with the lesion of ACL in 27 (69%) patients. In 28 (72%) patients bone bruise was in combination with the lesion of menisci. Only two patients with bone bruise had neither ACL nor menisci lesions. There were 78 patients without bone bruise but 33 (43%) of them had lesions of ACL and 49 (63%) had lesions of menisci. Conclusion. Bone bruise is best seen in STIR (Short TI Inversion Recovery) images and is very often found in acute knee trauma. Very often it is associated with posttraumatic lesions of ACL and menisci, so attention must be paid to this when bone bruise is seen. The difference in frequency of internal structures of the knee lesions in patients with bone bruise is highly statistically significant as compared to patients with no bone bruise.