The most common complications following total knee arthroplasty (TKA) are known to be developed in patellar component. Authors analysed those complications in 300 TKAs which were followed for at least one year (1-10 years) following surgery. The presence of subluxation or dislocation of the patellar component was determined by the congruence angle (??16). There was no case which showed patellar subluxation on the immediate postoperative rediographs. The results were as follows: l. Overall complication rate was 29 (9.7%). Seventeen cases (5.7%) had subjective symptoms including 10 subluxation, 4 postoperative patellar tendon rupture, 1 carbon induced synovitis with patellar meniscus, 1 patella alta, and 1 calcification of patellar tendon. However, 12 (4.0%) cases had only symptomless roentgenographic subluxation. 2. Symptomatic patellar complications developed in 7 out of 101 (6.9%) rheumatoid knees, whereas in 10 out of 199 (5.0%) non-rheumatoid knees (p>0.05). 3. Seven patellar subluxations developed in 6 Miller-Galante I and 1 Tricon M were surgically treated. The other 3 Miller-Galante I knees could not be operated on for other personal reasons. 4. The rate of roentgenographic subluxation or dislocation following TKA in Miller-Galante I was significantly higher in rheumatoid knees (11 out of 29, 37.9%) than non-rheumatoid knees (8 out of 39, 20.5%) (p<0.05). 5. Four knees had rupture of patellar tendon after TKA for fused knee. From these results, we conclude that precise surgical performance, proper selection of the implant, careful postoperative rehabilatation and follow-up at regular interval are mandatory to reduce the rate of patellar complications after TKA.